A Map of the Bitcoin Ecosystem [Last Update March 2026]

This is an attempt at a comprehensive, link-rich map of where “Bitcoin development” actually lives in early 2026: the specs, the reference implementation and its alternatives, the cryptography, the Lightning stack, the wallet engineering layer, the privacy tools, the chain-data infrastructure, the new layer-2 designs, mining, merchant tooling, the funding orgs, the Brazilian sub-ecosystem, and the businesses built on top. It tries to be useful both as an orientation document for someone walking in cold, and as a reference for people already inside who want to know where a given concept lives.

1. The Standards Layer

Bitcoin Improvement Proposals (BIPs)

BIPs are the formal documentation medium for Bitcoin’s protocol, P2P, wallet, and policy standards. The canonical repository is bitcoin/bips; the readable front-end is bips.dev. Anything that touches script, relay policy, P2P messaging, wallets, descriptors, or PSBT eventually goes through the BIP process.

The BIP process itself was overhauled for the first time in nine years when BIP 3 (by Mark “Murch” Erhardt) replaced BIP 2 in early 2025, simplifying statuses from nine to four (Draft, Complete, Deployed, Closed) and clarifying that editors check formatting rather than technical merit. In April 2024 five new editors (Bryan Bishop, Jon Atack, Murch, Roasbeef, Ruben Somsen) joined Luke Dashjr, ending a long-standing bottleneck. Technical discussion has migrated to the bitcoindev@googlegroups.com mailing list (moved from Linux Foundation hosting in February 2024) and the Delving Bitcoin forum.

Lightning specs (BOLTs)

The lightning/bolts repository is the in-progress home of the Basis of Lightning Technology documents. Implementations (LND, Core Lightning, Eclair, LDK) aim to be spec-compliant, and most cross-implementation interoperability friction is ultimately a BOLT interpretation question.

The BOLT lineup as of early 2026:

• BOLT 1: message framing and TLV encoding
• BOLT 2: channel lifecycle (open_channel, commitment_signed, revoke_and_ack, cooperative and unilateral close)
• BOLT 3: on-chain transaction formats and key derivation (per-commitment secrets, basepoints)
• BOLT 4: Sphinx onion routing with per-hop TLV payloads, route blinding
• BOLT 5: on-chain settlement, CPFP and RBF fee bumping recommendations
• BOLT 7: gossip protocol (channel_announcement, channel_update, node_announcement)
• BOLT 8: Noise_XK encrypted transport with ChaCha20-Poly1305 AEAD, key rotation every 1000 messages
• BOLT 9: feature flag registry (odd = optional, even = mandatory)
• BOLT 11: legacy bech32 invoice format
• BOLT 12: reusable offers (lno1...), recurring payments, blinded paths

BOLT 12 is the most significant addition since the original specs. Offers are reusable payment endpoints negotiated over onion messages piggybacking on existing LN connections (no external server). The payer fetches a fresh invoice from the payee, with blinded paths hiding the recipient’s node identity behind an encrypted introduction node. Bastien Teinturier (t-bast) of ACINQ drove much of the route-blinding spec. BIP 353 integrates this with human-readable names (₿user@domain.com) that resolve via DNS.

2. Bitcoin Core

Bitcoin Core is the reference implementation: full node, wallet, P2P stack, and consensus engine. ~88,000 GitHub stars, ~39,000 forks, one of the most-starred C++ repositories on GitHub. Releases ship from bitcoincore.org as signed deterministic binaries; the latest release is v29.3 (February 2026). The most recent stats from Jameson Lopp put the project at ~41 active developers (5+ merged commits), 135 unique contributors in 2025, 2,541 commits, and a 60% YoY jump in mailing-list traffic. Adjacent repos under the bitcoin-core org include the GUI staging repo, HWI, and the embedded crypto library at bitcoin-core/secp256k1.

Codebase architecture

src/ decomposes into clearly delineated modules:

• validation.cpp is the consensus-critical heart: CheckBlock(), ConnectBlock(), AcceptBlock(), ActivateBestChain().
• The P2P layer splits across net.cpp (TCP connections via CConnman) and net_processing.cpp (application-layer handling via PeerManager, dispatching VERSION/HEADERS/BLOCK/INV/TX into the validation engine).
• The mempool lives in txmempool.cpp as CTxMemPool, historically backed by a boost::multi_index_container with indices by txid, wtxid, descendant score, entry time, and ancestor feerate.
• The wallet lives under src/wallet/ with DescriptorScriptPubKeyMan for modern descriptor wallets and the deprecated LegacyScriptPubKeyMan.
• Script interpretation is in src/script/interpreter.cpp, which implements the stack-based Script VM.
• src/consensus/ isolates consensus parameters and src/rpc/ exposes JSON-RPC.

The block validation pipeline runs CheckBlockHeader() (context-free PoW), ContextualCheckBlockHeader() (timestamps and difficulty), CheckBlock() (merkle root, duplicate txs, per-tx checks), then ConnectBlock(), which enforces BIP 30, verifies inputs via CheckInputScripts(), and updates the UTXO set. Script checks are encapsulated in CScriptCheck closures and dispatched to CCheckQueue for parallel verification across CPU cores.

The UTXO set uses a layered cache: CCoinsViewDB (LevelDB persistent), CCoinsViewCache (in-memory layer for block connection), CCoinsViewMemPool (mempool-aware wrapper for spending unconfirmed outputs). Each entry is Coin = {CTxOut, height, is_coinbase}. Subsystems like the wallet and indexes register on CValidationInterface and receive async callbacks (BlockConnected, TransactionAddedToMempool, UpdatedBlockTip) via CMainSignals.

libbitcoinkernel

libbitcoinkernel is the in-progress effort to extract the validation engine into a reusable C library. Unlike the deprecated libbitcoinconsensus (which only validated scripts), libbitcoinkernel is a stateful engine managing threads, caching, I/O, and dynamic objects like the mempool. TheCharlatan (Sebastian Kung), who became a maintainer in January 2026, leads the work. The first iteration shipped in v30.0, with the C API under development in src/kernel/ and longer-term aspirations to compile for WASM and RISC-V (which would enable zero-knowledge validation). Out-of-tree wrappers exist already: TheCharlatan/rust-bitcoinkernel, stickies-v/py-bitcoinkernel, and setavenger/go-bitcoinkernel.

Build, CI, fuzzing

The build system migrated from Autotools to CMake in PR #30454 (Hennadii Stepanov, September 2024); v29 was the first CMake release. Reproducible builds use Guix (replacing Gitian since v22.0). CI runs across GitHub Actions and Cirrus with a matrix spanning GCC, Clang, ASan, MSan, TSan, UBSan, Valgrind, and fuzzing builds. There are 200+ fuzz targets under src/test/fuzz/, integrated with OSS-Fuzz since May 2021. Seed corpora live in bitcoin-core/qa-assets.

Review culture follows ACK/NACK: ACK with commit hash and test description signals approval, NACK requires technical justification, Concept ACK endorses the goal without code-level review. The Bitcoin Core PR Review Club meets twice monthly to onboard new contributors. The first public security audit (by Quarkslab, commissioned by Brink) landed in November 2025 with no critical vulnerabilities.

Maintainers (as of February 2026)

There are five maintainers with commit access. Their role is described as janitorial: they merge patches that already reflect contributor consensus.

Maintainer	Domain
Michael Ford (fanquake)	build system, CI, releases
Ava Chow (achow101)	wallet, PSBT, descriptors, HWI
Hennadii Stepanov (hebasto)	GUI, CMake migration
Ryan Ofsky (ryanofsky)	multiprocess architecture
TheCharlatan	libbitcoinkernel (added January 8, 2026)

Gloria Zhao stepped down February 5, 2026, revoking her PGP key amid the OP_RETURN controversy and personal attacks. That was a meaningful loss given her central role in mempool policy, package relay, and TRUC. Wladimir van der Laan (laanwj) led the project from 2014 to 2023 and remains the top all-time contributor by commits. Marco Falke, prolific in test infrastructure, resigned February 2023. Jonas Schnelli is a former maintainer who focused on GUI, networking, and encryption.

Historically essential contributors

Person	Contributions
Satoshi Nakamoto	Whitepaper (2008), initial codebase (2009), disappeared ~2011
Gavin Andresen	Early lead developer after Satoshi (2010-2014)
Pieter Wuille (sipa)	SegWit, Taproot/Schnorr (BIP 340-342), libsecp256k1, Miniscript, compact block relay
Gregory Maxwell (gmaxwell)	CoinJoin concept, Confidential Transactions, compact blocks, key Taproot contributions
Andrew Chow (achow101)	Descriptor wallets, PSBT, HWI
Matt Corallo (TheBlueMatt)	rust-lightning (LDK), BetterHash, compact block relay
Suhas Daftuar	P2P networking, block relay, mempool policy, Cluster Mempool
John Newbery	Founded Brink, ran Optech and PR Review Club
Andrew Poelstra (apoelstra)	Taproot, Schnorr, Miniscript, MuSig; Blockstream Research Director
Antoine Riard	Lightning security research, mempool policy
Jeremy Rubin	OP_CTV (BIP 119) proposer, Judica founder
Luke Dashjr	BIP 2 editor, BFGMiner, Knots client
Peter Todd	OpenTimestamps, RBF, security research
Adam Back	Hashcash inventor (cited in the whitepaper), Blockstream CEO
Sjors Provoost	wallet features, Stratum V2
Sebastian Falbesoner (theStack)	reviewer and test author
Martin Zumsande	P2P and address management (Chaincode Labs)
Amiti Uttarwar	mempool and P2P (OKX-funded)
Niklas Gögge (dergoegge)	security, fuzzing, testing (Brink)
Abubakar Nur Khalil	Bitcoin Core contributor, interim CEO of Btrust (2024)
0xB10C	network monitoring, transaction analysis tools

Recent technical milestones

Cluster Mempool (PR #33629, merged November 25, 2025 by Suhas Daftuar) fundamentally rearchitects mempool evaluation. The pre-cluster mempool used inconsistent orderings for mining (ancestor feerate) and eviction (descendant feerate) that were not inverses of each other, meaning eviction could remove the mempool’s best transaction during trimming, and RBF could not reliably evaluate whether a replacement improved miner revenue. Cluster Mempool partitions transactions into clusters (transitively connected unconfirmed transactions, capped at 64 transactions / 101 kvB), linearizes each cluster into optimal-feerate chunks using the Spanning Forest Linearization algorithm (a reduction to the 1989 maximum-ratio closure problem), and exposes a unified feerate diagram: mining selects highest-feerate chunks, eviction removes lowest-feerate chunks, RBF compares diagrams before and after. This eliminates ancestor/descendant limits, removes CPFP carve-out, and drops the legacy multi-index. The underlying TxGraph abstraction (PR #31363) knows nothing about CTransaction or txids, only fees, sizes, and dependencies. Expected to ship in Core v31.

Package Relay and TRUC (BIP 431, by Gloria Zhao) finally solve Lightning’s transaction-pinning problem. TRUC (“Topologically Restricted Until Confirmation”) transactions use nVersion=3 and enforce strict topology: one unconfirmed parent (up to 10 kvB), one child (≤1 kvB), always replaceable without BIP 125 signaling. Sibling eviction ensures either Lightning channel party can always fee-bump by evicting the other’s child. 1P1C (One-Parent-One-Child) relay pairs low-feerate parents with fee-paying children for joint evaluation, so TRUC parents can be zero-fee when packaged with a fee-paying child. Pinning previously let adversaries prevent counterparty transactions from confirming by attaching large low-feerate descendants or exhausting descendant limits. Ephemeral anchors (Gregory Sanders) replace the old dual-anchor design with a single zero-value OP_TRUE output that must be spent in the same package; standardized as Pay-to-Anchor (P2A) in Core 28.0, with ephemeral dust support in v29.0, this lets anyone (not just channel parties) create the fee-paying child.

AssumeUTXO (James O’Beirne, available on mainnet since v28.0) loads a serialized UTXO set snapshot at a hardcoded block height (840,000 for mainnet) and immediately begins validating new blocks while a background chainstate replays all historical blocks. Once the background validation catches up, the snapshot’s integrity is confirmed by hash comparison. This is structurally different from AssumeValid, which only skips script validation but still processes every block.

Other recent relay changes. Full RBF became unconditional in v29.0 (the -mempoolfullrbf option was removed). Default minimum relay feerate dropped to 0.1 sat/vB in v29.1 after miners began including sub-1-sat/vB transactions. Core v30.0 improved 1P1C relay to handle broader topologies, added wallet TRUC support, and introduced DoS-resistant orphanage limits based on weight and input count per peer.

3. Alternative Node Implementations

Alternative implementations matter for wallet backends, SPV/light clients, and cross-implementation correctness testing. The historically canonical warning about consensus-level diversity is the 2013 BDB/LevelDB fork (BIP 50): when Core v0.8 switched to LevelDB, the BDB lock limit of 10,000 became an implicit consensus rule, and block 225,430 exceeded it. LevelDB nodes accepted the block, BDB nodes rejected it, the chain split, and resolution required all miners to downgrade to v0.7, coordinated within an hour on IRC. At least one double-spend occurred during the fork. Even database-level implementation differences can cause consensus failures.

• btcd (Go, ~6,100 stars). Alternative full node in production since 2013, part of the btcsuite ecosystem (btcec, btcutil) imported by 1,855+ Go packages. Best known as LND’s dependency, which became a vulnerability in October-November 2022 when developer “Burak” twice exploited consensus divergences (btcd’s P2P layer still enforced pre-Taproot script size limits). Because LND used btcd’s wire parsing even when running atop Bitcoin Core, all LND nodes were vulnerable regardless of their full node.
• bcoin (JavaScript, ~3,000 stars). Full node capable of running in browsers via WebSocket proxy. Targets enterprise applications and exchanges.
• libbitcoin (C++, ~1,000+ stars). The oldest alternative implementation (founded 2011 by Amir Taaki). ZeroMQ-based server architecture designed for public indexing, architecturally distinct from Core’s local-client RPC design.
• Bitcoin Knots (Luke Dashjr). Applies patches atop Core, sharing consensus but diverging on relay policy. The 2025 OP_RETURN controversy drove Knots adoption from 69 nodes (January 2024) to an estimated 17-25% of public nodes by late 2025. Core v30.0 raised -datacarriersize to ~100,000 bytes (effectively uncapping OP_RETURN), with 31 senior contributors signing a statement supporting neutral relay. Dashjr and allies argued this enables Ordinals/Runes “spam” and creates regulatory attack vectors. This is policy-level divergence, not consensus divergence: both implementations accept identical blocks.
• Floresta (Rust). Lightweight full-validating node using the Utreexo accumulator for compact UTXO representation, delegating script validation to rust-bitcoinconsensus to avoid reimplementing consensus. Brazilian developer Davidson Souza leads it under a Vinteum grant.

BitcoinJ (JVM, ~5,000 stars) is still widely used for Android SPV wallets and historical tooling.

4. Cryptographic Primitives

libsecp256k1

bitcoin-core/secp256k1 (~2,400 stars) is a high-assurance C library for elliptic curve operations on the secp256k1 curve, created by Pieter Wuille to replace Bitcoin Core’s OpenSSL dependency. Motivations: deterministic behavior for consensus, constant-time execution to prevent side-channel attacks, raw performance. Current benchmarks show libsecp256k1 is over 8x faster than OpenSSL for ECDSA verification (~47.6 µs vs ~475 µs per signature).

Modules cover ECDSA, Schnorr (BIP 340), MuSig2 (BIP 327, added in v0.6.0 in November 2024), ECDH, key recovery, and ElligatorSwift (for BIP 324 v2 encrypted P2P transport). The security model guarantees constant-time, constant-memory-access operations for all secret-key code, with no heap allocation and no floating-point types.

Maintained by Tim Ruffing (real-or-random), Jonas Nick, and Pieter Wuille.

Schnorr signatures and Taproot

BIP 340 Schnorr signatures use s = k + e·x with e = H(R||P||m), producing compact 64-byte signatures versus ECDSA’s variable 70-72 byte DER encoding. The critical advantage is linearity: because s·G = R + e·P decomposes additively, multiple signers’ contributions combine algebraically. That enables key aggregation (MuSig2), batch verification (checking n signatures with a single multi-scalar multiplication), and simple security proofs. X-only public keys (32 bytes, implicitly choosing the even y-coordinate) save another byte over compressed ECDSA keys. Tagged hashes (SHA256(SHA256(tag) || SHA256(tag) || data)) prevent cross-protocol attacks.

Taproot (BIP 341) constructs a tweaked public key Q = P + H("TapTweak" || P || merkle_root) · G that encodes two spending paths. The key path needs only a Schnorr signature for Q, which is indistinguishable from single-sig on-chain. The script path reveals the internal key P, a Merkle proof of sibling hashes, and satisfies a leaf script under Tapscript (BIP 342). Tapscript replaces OP_CHECKMULTISIG with OP_CHECKSIGADD for batch-verifiable k-of-n constructions, introduces OP_SUCCESS opcodes reserving undefined opcodes for future soft-fork upgrades, and removes per-leaf script size limits.

Taproot activated at block 709,632 on November 12, 2021 via Speedy Trial after a 90% miner signaling window (Russell O’Connor’s compromise after the BIP 8 LOT=true/LOT=false debate that followed SegWit’s contentious activation).

MuSig2 and FROST

MuSig2 (BIP 327) is n-of-n multisig that produces a single aggregate public key and single signature on-chain, using a two-round protocol. Round 1: each signer publishes two public nonces (R1_i, R2_i). Round 2: a binding coefficient b = H(R1||R2||P_agg||m) combines the nonces into R = R1 + b·R2, and each signer produces a partial signature s_i = k1_i + b·k2_i + e·a_i·x_i. The final (R, Σs_i) is a standard BIP 340 signature. Key aggregation uses per-key coefficients a_i = H(L||P_i) where L = H(P_1||...||P_n). Non-experimental in libsecp256k1 v0.6.0 (2024).

FROST (RFC 9591) extends this to t-of-n threshold signatures. Any t signers can produce a valid signature using Lagrange interpolation coefficients during signing. A Distributed Key Generation phase distributes key shares without any single party ever possessing the full secret. Implementations exist in Rust (ZcashFoundation/frost with secp256k1 ciphersuite) and Go (Coinbase’s MPC infrastructure). FROST’s tradeoff versus MuSig2 is the required DKG setup and stronger security assumptions (OMDL vs DL).

Miniscript

Miniscript (Pieter Wuille, Andrew Poelstra, Sanket Kanjalkar) provides a structured representation between human-readable policies and Bitcoin Script. Its type system classifies expressions as B (Base), V (Verify), K (Key), or W (Wrapped), with modifiers for dissatisfiability, non-malleability, and signature requirements. A policy like and(pk(A), or(99@pk(B), older(12960))) compiles to and_v(v:pk(A), or_d(pk(B), older(12960))) in Miniscript, then to concrete Bitcoin Script opcodes.

Bitcoin Core added Miniscript in v24 (watch-only), v25 (signing), and v26 (Tapscript context). The critical capability: any Miniscript-aware wallet can finalize any Miniscript-based PSBT generically, eliminating the need for script-specific finalizers and enabling true cross-vendor interoperability. The Rust reference is rust-bitcoin/rust-miniscript.

The wallet engineering stack

Three technologies, taken together, define modern wallet engineering: Output Descriptors, Miniscript, and PSBT. Descriptors tell wallets what scripts to generate, Miniscript reasons over them (spending conditions, witness sizes, signing requirements), and PSBT provides the collaborative transaction construction workflow.

PSBT v0 (BIP 174) defined a binary format with six workflow roles: Creator, Updater, Signer, Combiner, Finalizer, Extractor. PSBT v2 (BIP 370) decomposed the unsigned transaction into per-input/per-output fields, enabling dynamic modification after creation. BIPs 327, 373, and 390 integrated MuSig2 into the stack with dedicated PSBT fields and descriptor syntax.

The historical BIP lineage that anchors modern wallets:

• BIP 32 (Pieter Wuille, 2012): hierarchical deterministic wallets using HMAC-SHA512 key derivation, extended keys (xpub/xprv), hardened and non-hardened child derivation.
• BIP 39: 128-256 bits of entropy plus SHA-256 checksum mapped to 12-24 mnemonic words, 512-bit seed via PBKDF2 with 2048 rounds.
• BIP 44: derivation paths as m/purpose'/coin_type'/account'/change/address_index.
• BIP 141 (SegWit) (activated August 2017): separated witness data at 1 weight unit per byte vs 4 WU for non-witness data, creating the 4 MWU block weight limit and fixing transaction malleability. SegWit was the prerequisite for Lightning.
• BIP 16 (P2SH) (2012, Gavin Andresen): pay to script hash, complex scripts behind simple addresses.

5. Active BIP Proposals

Proposal	Driver	What it does
BIP 119 (OP_CTV)	Jeremy Rubin	Covenants via transaction-template commitments. Enables vaults, congestion control, payment pools.
BIP 347 (OP_CAT)	Ethan Heilman, Armin Sabouri	Re-enables byte concatenation in Tapscript. 74,000+ signet transactions demo’d potential for STARKs and covenants.
BIP 345 (OP_VAULT)	James O’Beirne	Targeted vault construction with interruptible, timelocked withdrawals.
BIP 118 (SIGHASH_ANYPREVOUT)	AJ Towns, Christian Decker	Enables LN-Symmetry (eltoo), non-punitive channel updates.
BIP 352 (Silent Payments)	Ruben Somsen	Stealth-address-like privacy without consensus changes. Wallet support landing in Cake, BitBox02, Nunchuk.
BIP 360 (P2TSH / formerly P2QRH)	Hunter Beast	Quantum preparedness: removes key-path spend from Taproot (witness version 2). Post-quantum signature algorithms via separate BIPs.
OP_CHECKSIGFROMSTACK	Various	Lets BitVM-style systems verify single signatures over state transitions instead of thousands of individual bits.
OP_TXHASH	Various	Generalization of CTV.

Cluster Mempool, Package Relay, and AssumeUTXO are mentioned above; they are non-consensus changes but are the most consequential protocol-adjacent work since Taproot.

6. Lightning Network

The Lightning Network turns Bitcoin from a settlement ledger into a payment network by layering bidirectional payment channels atop the base chain. A channel is, at the Bitcoin transaction level, a 2-of-2 multisig output (or, post-Taproot, a MuSig2-aggregated P2TR key-path output) whose spending requires both parties’ cooperation. Commitment transactions, held off-chain by each participant, represent the current channel state. The revocation mechanism enforces honesty: each new state discloses the prior state’s revocation key, so broadcasting a stale commitment lets the counterparty sweep the cheater’s entire balance via a breach remediation transaction.

The four implementations

LND (~8,100 stars, Go, by Lightning Labs). Most widely deployed implementation. gRPC-first API, pluggable chain backends (bitcoind, btcd, Neutrino). Architected by Olaoluwa Osuntokun (roasbeef). First to ship Simple Taproot Channels (v0.17, October 2023), though limited to private channels pending gossip protocol updates. Latest: v0.20.0-beta (November 2025). Product suite includes Loop (submarine swaps), Pool (liquidity auctions), and Taproot Assets (formerly Taro), whose v0.7 release (December 2025) enables stablecoin transfers like USDT and DePix over Lightning. LND does not natively support BOLT 12, but LNDK (Carla Kirk-Cohen, Lightning Labs) shims LDK’s BOLT 12 onto LND’s gRPC interface. Strike’s BOLT 12 deployment runs through LNDK.

Core Lightning (CLN) (~3,000 stars, C, by Blockstream). Radically modular: the core daemon handles only channel state; everything else lives in plugins, external processes communicating via JSON-RPC stdin/stdout. Designed by Rusty Russell, who also authored most of the original BOLTs. Pioneered BOLT 12 in production (v0.12, August 2022), dual-funded channels (Lisa Neigut’s interactive-tx protocol and liquidity ads), and production splicing with cross-implementation interop achieved alongside Eclair in v25.05. The v25.12 release (December 2025) added BIP-39 mnemonic seed backup as default and continued refining the xpay/askrene payment engine, a minimum-cost-flow solver by @Lagrang3 (Eduardo de Lorenzo) that natively implements Pickhardt-Richter routing. Greenlight, Blockstream’s managed CLN service, runs over 200,000 nodes. The commando plugin enables remote RPC access authenticated by rune-based tokens.

Eclair (~1,320 stars, Scala, by ACINQ). Built atop the Akka actor framework, with each channel as an actor managing its own state machine. Eclair has been the leading implementation for splicing in production, with dual funding plus splicing in Simple Taproot Channels landing in August 2025 (PR #3103). Phoenix v2.7.0’s Taproot channel support showed ~20% on-chain fee reduction and cooperative closes indistinguishable from standard P2TR wallet spends. Bastien Teinturier drives Eclair’s protocol work on BOLT 12, blinded paths, trampoline routing, and payment decorrelation. v0.13.1 requires Bitcoin Core 29.x and is the last release supporting pre-anchor channels.

LDK / rust-lightning (~1,330 stars, Rust, by Spiral / Block). Library, not a node: modular Lightning primitives (channel management, routing, signing, persistence interfaces) without imposing networking, storage, or chain-sync choices. Runtime-agnostic, suitable for mobile, embedded, and server environments. Matt Corallo is the core maintainer. LDK 0.2 (December 2025) introduced experimental splicing, static invoices for asynchronous payments, and zero-fee-commitment channels with ephemeral anchors. LDK Node wraps it into a ready-to-go node, and language bindings cover Java/Kotlin, Swift, JavaScript, and Python. Powers Bitkey’s Lightning integration (via BDK for on-chain, LDK for Lightning) and the iOS implementation of Phoenix.

Routing: Pickhardt-Richter and beyond

Lightning pathfinding is source-routed: the sender must find a path through the channel graph before constructing the onion packet. All implementations use Dijkstra variants running backward from destination to source (to properly accumulate fees), but the cost functions diverge sharply. Routing is deliberately unspecified in the BOLTs, so it is where competitive differentiation lives.

The fundamental challenge is liquidity uncertainty: gossip advertises capacity but not balance distribution. A 1 BTC channel might have 0.9 BTC on one side or 0.1. Early routing treated channels as binary (available or not), producing frequent failures.

René Pickhardt and Stefan Richter’s 2021 paper (Optimally Reliable & Cheap Payment Flows on the Lightning Network) transformed this by modeling unknown channel balances as uniform random variables over [0, capacity]. The probability of successfully forwarding amount a through a channel of capacity c becomes (c - a) / c. Negative logarithms convert multiplicative path probabilities into additive costs amenable to standard shortest-path algorithms. For multi-path payments, the optimal splitting strategy is a minimum-cost flow problem with separable convex cost, solvable in polynomial time. The framework also exposed why base fees create a concavity at the 0→1 flow transition that makes the optimization NP-hard, driving the #zerobasefee movement.

In production, LND implements this through its Mission Control system (routing/missioncontrol.go), tracking success and failure amounts per directed node pair with configurable decay half-lives. The bimodal probability estimator in v0.16 applies the math but assumes a U-shaped liquidity distribution rather than uniform, matching empirical observations that most channels are skewed. Joost Jager authored the core Mission Control PRs. CLN’s askrene plugin goes further, implementing a native min-cost-flow solver. LND multi-path payments use a divide-and-conquer splitting strategy, while CLN computes globally optimal flow allocations.

Taproot channels, LN-Symmetry, and gossip reform

Simple Taproot Channels upgrade funding and commitment transactions from P2WSH 2-of-2 to P2TR outputs where the internal key is a MuSig2 aggregate. Cooperative closes produce a single 64-byte Schnorr signature indistinguishable from any single-sig Taproot transaction. More importantly, Taproot channels are the foundation for PTLCs (Point Time-Locked Contracts), which replace HTLCs’ hash preimage reveal with adaptor signatures on distinct curve points per hop. Where HTLCs use the same payment hash across the entire route (enabling correlation by colluding routing nodes), PTLCs use different points at each hop, providing payment decorrelation and eliminating the wormhole attack. PTLCs are not yet deployed but the scaffolding is in place.

Public Taproot channels are blocked by the gossip protocol limitation: BOLT 7’s channel_announcement proves channel existence via a P2WSH output and ECDSA signatures, which does not work for P2TR outputs with Schnorr / MuSig2 aggregate keys. Elle Mouton’s gossip v1.75 proposal (bolts PR #1059) introduces channel_announcement_2, channel_update_2, and node_announcement_2 messages supporting BIP-340 Schnorr signatures and TLV fields. The “v1.75” label distinguishes this proof-per-channel approach from a full gossip v2 that would decouple UTXO proofs from channels entirely.

LN-Symmetry (originally eltoo), invented by Christian Decker, proposes a different channel update mechanism where any later state can replace any earlier state, eliminating the asymmetric penalty model. Both parties hold identical transaction structures (hence “symmetry”), and broadcasting a stale state merely wastes fees rather than risking total forfeiture. That dramatically simplifies backups, makes hardware-wallet Lightning signing viable, and enables multiparty channel factories. LN-Symmetry requires BIP 118 (SIGHASH_ANYPREVOUT), a new sighash mode where signatures do not commit to the specific UTXO being spent. Greg Sanders at Chaincode Labs built a CLN-based proof-of-concept on Bitcoin Inquisition’s custom signet. BIP 118 is unactivated as of February 2026.

Liquidity and watchtowers

The liquidity management problem has spawned dedicated marketplaces. Lightning Pool is a non-custodial sealed-bid auction by Lightning Labs that packages inbound liquidity as fixed-income assets (Lightning Channel Leases) with block-denominated maturity. Magma by Amboss takes a P2P approach using HODL invoices, working across all implementations. Lisa Neigut’s liquidity ads spec (BOLT PR #878) integrates with dual-funded channels: nodes advertise rates via node_announcement feature flags. The LSP specification (BitcoinAndLightningLayerSpecs/lsp, archived January 2025) defines standardized APIs for LSPs, with LSPS2 specifying JIT channels where the LSP intercepts an incoming payment and opens a zero-conf channel deducting fees before forwarding.

Watchtowers monitor the blockchain for revoked commitment transactions and broadcast penalty transactions on the user’s behalf. The Eye of Satoshi (rust-teos) (~140 stars), by Sergi Delgado, is the primary BOLT 13-compliant reference. The client sends encrypted blobs keyed to truncated commitment txids; the watchtower can only decrypt and act when a matching breach appears on-chain. LND ships a built-in watchtower server and client; CLN’s chanbackup plugin effectively turns peers into lightweight watchtowers via peerstorage. Under LN-Symmetry, watchtower requirements simplify dramatically: only the latest state needs storage.

Lightning tooling

Project	Stars	Purpose
LNbits	~1,500	Custodial accounts layer atop CLN, LND, phoenixd, Eclair, or Nostr Wallet Connect. Each wallet gets admin and invoice-only API keys. 70+ extensions (LNURL-pay, point-of-sale, tipping, Bolt Cards). Dominant platform for hackathons.
Zeus	~1,175	Mobile BTC/LN wallet and remote node manager. v0.12.0-rc1 (Dec 2025) added watchtowers, hybrid Lightning addresses, BIP-353/BOLT-12. Maintained by Evan Kaloudis.
Alby Hub	~600	Self-sovereign LN node with Nostr Wallet Connect, sub-wallets, auto-swaps, app store. LDK-based embedded node.
Balance of Satoshis	~610	CLI for LND node management (rebalancing, fees, accounting, Telegram bot via bos telegram). By Alex Bosworth.
Blixt Wallet	~395	Non-custodial mobile LN wallet with on-device LND + Neutrino SPV. Lightning Box for LN addresses. HRF grantee.
RTL (Ride the Lightning)	~600	Full-function web UI for LND/CLN/Eclair node management.
ThunderHub	~500	Lightning Node Manager web UI.
Polar	~700	One-click Lightning Network dev environment.
lndinit	~50-100	LND initialization utility for containerized/Kubernetes deployments.

Lightning-first wallets include Phoenix (~820 stars, ACINQ, splicing-based single dynamic channel per wallet, mobile), phoenixd (~153 stars, server daemon version with HTTP API, v0.7.0 in Oct 2025 added Taproot channel support), Muun (~500), Breez (~400), Phoenix (self-custodial mobile LN), and Wallet of Satoshi (custodial, integrated with Spark).

7. Wallet Engineering

Rust ecosystem

rust-bitcoin/rust-bitcoin (~2,500 stars, CC0 license) is owned by Andrew Poelstra and Matt Corallo and provides Bitcoin protocol primitives (Transaction, Block, Script, Address, PSBT). Hierarchical crates underneath include bitcoin-hashes and secp256k1-rs. rust-miniscript (~411 stars) implements Miniscript and Output Descriptors. All crates support no_std for embedded environments. The popular rust-bitcoincore-rpc was archived November 2025 and replaced by corepc-client.

BDK (Bitcoin Dev Kit) (~1,000 stars, by the bitcoindevkit org) uses Output Descriptors as the fundamental wallet abstraction. Chain data sources are pluggable: bdk_electrum for Electrum servers, bdk_esplora for Esplora HTTP, bdk_bitcoind_rpc for direct Core RPC, bdk_kyoto for BIP 157/158 compact block filters. bdk-ffi uses Mozilla’s UniFFI to generate Swift (iOS), Kotlin (Android), and Python bindings. Notable adopters include Proton Bitcoin Wallet and the Bark Ark implementation. Maintainers: Evan Lin (evanlinjin), Leonardo Lima (oleonardolima). Site: bitcoindevkit.org. Index of related projects: awesome-bdk.

JavaScript, Python, .NET, Java

Library	Stars	Notes
bitcoinjs-lib	~5,800	Browser and Node.js Bitcoin library. Taproot, PSBT. v6.1.7 (Dec 2024); v7.0.0-rc.0 in dev. 41-repo org. Maintainer: Jonathan Underwood. Even widely used libs accumulate technical debt: a public critical assessment of bitcoinjs-lib’s design exists, and the broader JS ecosystem has seen real supply-chain attacks (the 2018 event-stream incident; three malicious npm packages impersonating the bitcoinjs ecosystem in November 2025).
bitpay/bitcore	~3,800	BitPay’s full-stack monorepo: Bitcore Node, Insight explorer, wallet, P2P. Multi-chain.
python-bitcoinlib	~1,900	Python3 interface to Bitcoin data structures, by Peter Todd. LGPL v3+.
NBitcoin	~1,900	Comprehensive .NET Bitcoin library by Nicolas Dorier. Powers BTCPay Server and Wasabi Wallet. 5.9M+ NuGet downloads. v9.0.5 actively maintained.
bitcoinj	~5,000	JVM Bitcoin library, used by many Android wallets.
libwally-core	~300	Blockstream wallet primitives in C, with Python, Java, and WASM bindings. Powers Blockstream Green and supports Liquid/Elements confidential transactions.
HWI	~566	Hardware Wallet Interface. By Ava Chow. Unified Python CLI/library for Trezor, Ledger, Coldcard, BitBox02, Jade. v3.2.0 (Feb 10, 2026) added Jade Plus and BitBox02 Nova. Integrates with Core’s PSBT workflow.
bech32	~600	Reference implementations of Bech32/Bech32m (Pieter Wuille).
programmingbitcoin	~1,830	Jimmy Song’s O’Reilly book companion. Teaches from-scratch Bitcoin coding in Python.

Desktop and mobile wallets

Wallet	Repo	Notes
Sparrow	sparrowwallet/sparrow, ~1,900 stars, Java	Desktop, security-focused. v2.4.1 (Feb 2026). Silent Payments (BIP 352), BIP 353, PSBTv2. Reproducible builds. Solo developer: Craig Raw.
Electrum	spesmilo/electrum, ~7,800 stars, Python	Veteran lightweight wallet since 2011. Lightning via trampoline routing. Desktop and Android. Thomas Voegtlin, SomberNight.
Wasabi	WalletWasabi/WalletWasabi, ~2,500 stars, C#	Privacy-focused with WabiSabi CoinJoin. Built-in Tor. Silent Payments send support. Avalonia UI. Lucas Ontivero (lontivero), turbolay.
BlueWallet	BlueWallet/BlueWallet, ~3,000 stars	iOS/Android thin client. Lightning via LNDHub. PSBT, multisig, watch-only.
Specter Desktop	cryptoadvance/specter-desktop, ~1,800 stars, Python	GUI for Core focused on multisig with hardware wallets.
Nunchuk	nunchuk-io/nunchuk-android	Multisig-first mobile wallet. Inheritance planning. Powered by libnunchuk C++ SDK. CEO Hugo Nguyen.
Bitcoin Wallet	bitcoin-wallet/bitcoin-wallet, ~3,500 stars	Long-running SPV wallet for Android.
Samourai	Samourai-Wallet	Privacy wallet (Whirlpool CoinJoin). Founders arrested April 2024; see Privacy section.
Green	Blockstream/green_android	Blockstream’s Bitcoin and Liquid wallet.

Hardware signing devices

Hardware wallets span a spectrum of security philosophies.

• Coldcard (Coldcard/firmware, ~800 stars). PSBT-native, by Coinkite. Mk4 has dual secure elements (Microchip ATECC608A + Maxim DS28C36B), NFC and MicroSD air-gap, trick PIN and brick PIN duress features. Coldcard Q adds a QWERTY keyboard, QR scanner, dual MicroSD slots, AAA batteries. Recent firmware (v5.4.5/v6.4.1X) added miniscript wallet support (BIP-388), tapscript signing, spending velocity policies.
• Foundation Passport (Foundation-Devices/passport2, ~300 stars). Open-source hardware (CERN Open Hardware License), STM32H7, power-only USB-C (no data pins). Passport Prime is a forthcoming Rust-based KeyOS device with sandboxed apps.
• SeedSigner (SeedSigner/seedsigner, ~600 stars). Radical air-gap DIY signer from Raspberry Pi Zero (no WiFi/Bluetooth), camera module, Waveshare LCD. No persistent storage: seeds exist only in volatile RAM.
• Trezor (trezor/trezor-firmware, ~1,300 stars). Model T, Safe 3 (entry-level, EAL6+ SE), Safe 5 (color touchscreen). Safe 7 features Tropic01, billed as the world’s first transparent and auditable secure element from sister company Tropic Square. SLIP-39 Shamir Secret Sharing backup.
• Ledger (LedgerHQ/app-bitcoin-new, ~200 stars). Nano S Plus, Nano X (Bluetooth), Flex, Stax (curved E-Ink). Proprietary ST33 secure element running BOLOS OS. The 2023 Ledger Recover controversy (firmware enabling encrypted seed shard export to third parties) prompted further code open-sourcing. Miniscript support landed in Bitcoin app v2.1.0.
• BitBox02 (BitBoxSwiss/bitbox-wallet-app, ~500 stars). Swiss-made open-source companion app.
• Bitkey (Block). 2-of-3 multisig across mobile app, hardware (fingerprint sensor, NFC, no screen), and Block’s recovery server. No seed phrase: recovery uses trusted contacts and a 7-day delay. BDK-based and open-source.
• Jade (Blockstream). Compatible with HWI via bitcoin-core/HWI.

8. Privacy

Bitcoin’s UTXO model publishes all amounts and spending relationships on a permanent public ledger, creating a structural privacy challenge that no amount of pseudonymity can fully address. The common-input-ownership heuristic assumes all inputs to a transaction are controlled by one entity, enabling wallet clustering at scale. Change output detection (via round-number heuristics, script-type mismatches, deterministic output ordering) further narrows anonymity. Address reuse provides direct linkage. Combined with exchange KYC data, IP-address correlation from transaction broadcast, and timing analysis, these heuristics power a commercial chain analytics industry (Chainalysis, Elliptic, TRM Labs) that processes billions of dollars in traceable flows.

CoinJoin

Gregory Maxwell’s 2013 CoinJoin proposal introduced the foundational idea: multiple parties combine inputs and outputs into a single transaction, breaking the common-input-ownership heuristic. The three major implementations reflect fundamentally different approaches to the coordinator problem.

JoinMarket (~750-800 stars, Python), by Adam Gibson (waxwing), eliminates the coordinator entirely. Its maker-taker model is a decentralized market: makers run YIELDGEN bots that advertise liquidity offers over IRC/onion relays, earning fees set by supply and demand; takers initiate CoinJoins, paying makers plus miner fees. The fidelity bond system (using BIP-65 timelocked coins) makes Sybil attacks expensive: maker selection probability scales superlinearly with bond value, computed as (locked_coins × (exp(rate × locktime) - 1))^1.3, with 87.5% of maker selection weighted by fidelity bond value and 12.5% random. Sybil resistance without any central authority. Latest v0.9.11.

Wasabi went central-coordinator but solved the privacy problem cryptographically through the WabiSabi protocol, replacing the original ZeroLink blind-signature scheme used in Wasabi 1.0. WabiSabi uses keyed-verification anonymous credentials (KVACs) with Pedersen commitments: during input registration, the coordinator issues MACs on committed (hidden) amount attributes; during output registration, users randomize their credentials and prove valid issuance via zero-knowledge proofs without the coordinator being able to link inputs to outputs. The additive homomorphism of Pedersen commitments (C1 + C2 = (v1+v2)·G + (r1+r2)·H) enables proving that outputs sum correctly without revealing individual amounts. This was the key advance over ZeroLink, which required fixed-denomination pools producing “toxic change” from leftover amounts. WabiSabi supports arbitrary output sizes in a single round, enabling hundreds of participants with unequal amounts. However, zkSNACKs (the default coordinator company) ceased CoinJoin coordination in June 2024 following the Samourai arrests. Third-party coordinators (Ginger, OpenCoordinator) emerged but face their own censorship pressures. Wasabi v2.6.0 “Prometheus” eliminated dependency on any centralized backend by supporting direct Bitcoin Core RPC.

Samourai Whirlpool used ZeroLink-style fixed-denomination pools (0.5, 0.05, 0.01 BTC) with blind signatures and a centralized coordinator, alongside complementary tools: Stowaway (a PayJoin implementation), StonewallX2, Ricochet. The April 2024 arrest of founders Keonne Rodriguez and William Lonergan Hill by SDNY, charged with conspiracy to operate an unlicensed money transmitting business and money laundering, sent shockwaves through the privacy tooling ecosystem. Both pled guilty in July 2025 to the lesser money laundering charge (the money transmitting charge was dropped); Rodriguez received 60 months and Hill 48 months in November 2025. The critical detail: FinCEN’s own internal analysis concluded Samourai’s non-custodial architecture did not constitute money transmission, but this was never disclosed to the defense. The anonymous Ashigaru fork revived Whirlpool in June 2025 as a Tor-only service with Electrum server backends, inheriting the centralized coordinator model.

Joinstr is an emerging approach: CoinJoin coordination over Nostr relays, replacing the central coordinator with censorship-resistant messaging. Still experimental and lacking JoinMarket-grade Sybil resistance.

PayJoin (BIP 78 / BIP 77)

PayJoin (BIP 78) breaks the common-input-ownership heuristic more directly than CoinJoin: both sender and receiver contribute inputs to a single payment transaction, making it impossible to determine which inputs belong to which party. The original BIP 78 required the receiver to host a public HTTPS server, severely limiting adoption. BIP 77 (Payjoin v2), driven by Dan Gould and the Payjoin Foundation, removes this constraint via asynchronous coordination through an untrusted store-and-forward directory, with OHTTP relays for metadata protection and HPKE for end-to-end encryption.

The rust-payjoin crate implements both versions. Cake Wallet shipped Payjoin v2 in May 2025; Bull Bitcoin Mobile followed. The Payjoin Foundation, launched August 2025 as a nonprofit modeled on Let’s Encrypt, aims to make PayJoin a universal default.

Silent Payments (BIP 352)

BIP 352, by Ruben Somsen, solves address reuse without notification transactions. The recipient publishes a static address encoding scan and spend public keys (B_scan, B_spend). A sender computes a shared secret via ECDH using the sum of their input private keys and the recipient’s scan key, then tweaks the spend key to derive a unique Taproot output per payment: P_k = B_spend + hash(shared_secret || k)·G. Each payment to the same silent address produces a distinct, unlinkable on-chain output.

The tradeoff is computational: receivers must scan every transaction with eligible inputs and Taproot outputs, performing ECDH for each candidate. A separate scan key enables watch-only wallets (detection without spending capability). Compared to BIP 47 PayNyms (which require an on-chain notification transaction creating sender-receiver linkage), BIP 352 eliminates that cost entirely. Implementation has progressed across Cake Wallet (full send + receive), BitBox02 and Wasabi (send-only), and a new bdk-sp crate for BDK-based wallets. BIP 375 (merged 2025) specifies Silent Payment integration with PSBTs.

CoinSwap and statechains

CoinSwap (citadel-tech/coinswap, ~115 stars), reviving Chris Belcher’s original teleport-transactions, provides stronger anonymity than CoinJoin by actually moving coins between unconnected UTXOs through atomic cross-party swaps. With Taproot plus MuSig2, the funding transactions are indistinguishable from standard single-sig spends. The privacy benefit extends to non-users: any transaction might be a CoinSwap, creating universal doubt in the transaction graph. The Citadel-Tech team has revived the protocol with a Taproot-MuSig2 implementation featuring a public CoinSwap marketplace on Mutinynet, though mainnet deployment remains experimental.

Mercury Layer (~54 stars) implements the statechain concept (originated by Ruben Somsen) for off-chain UTXO ownership transfer. A user and the Statechain Entity hold a 2-of-2 shared key where neither party knows the full private key. Transfers rotate the server’s key share such that the new owner’s share combines with the updated server share to produce the same aggregate public key. The critical trust assumption: the server must honestly delete old key shares. Blind signing ensures the server cannot learn the UTXO address, public key, or any transaction details. All verification (locktime decrementing, backup transaction validity) is client-side.

Network-level privacy

Transaction broadcast deanonymization (identifying the IP address that first propagated a transaction) remains an underappreciated threat. Dandelion++ (BIP 156) proposed a stem-then-fluff relay pattern with formal population-level anonymity guarantees, but was never merged into Core due to DoS concerns. What did ship is BIP 324 (v2 encrypted P2P transport), enabled by default since Core v27.0: ElligatorSwift-encoded key exchange producing a fully pseudorandom bytestream with ChaCha20-Poly1305 AEAD, indistinguishable from random data, raising the cost floor for ISP-level surveillance. Core also supports Tor (automatic v3 onion service creation), I2P (SAM v3.1 API, since v22.0), and CJDNS (since v23.0).

Taproot’s privacy properties compound across domains: a cooperative channel close, a 3-of-3 multisig spend, and a single-user payment all produce identical on-chain fingerprints (a P2TR output spent with one 64-byte Schnorr signature). MuSig2 aggregation makes n-of-n multisig indistinguishable from single-sig at the consensus level.

The regulatory inflection

The Samourai arrests, combined with the Tornado Cash prosecution (Roman Storm convicted of conspiracy to operate an unlicensed money transmitting business in August 2025, though the jury deadlocked on money laundering and sanctions charges), produced a chilling effect measurable in developer participation: U.S.-based contributors to open-source crypto projects declined from 25% to 18% of global contributors. Phoenix Wallet withdrew from U.S. app stores; Wasabi ceased mixing; Blink geofenced American users. The CLARITY Act (H.R. 3633), passed by the House in July 2025 with a 294-134 bipartisan vote, offers potential relief: Section 109 explicitly protects developers who publish or maintain code without controlling customer funds. Senate markup was ongoing in early 2026. The DOJ’s April 2025 policy shift (“Ending Regulation by Prosecution”) stated that developers of “truly decentralized” protocols will not face charges without explicit criminal intent, though the line between decentralized protocol and operational service remains contested.

9. Chain Data Infrastructure

Electrum servers

The Electrum protocol enables lightweight wallets to query chain data via JSON-RPC over TCP/SSL, with clients subscribing to script hashes. Three implementations cover different needs:

• electrs (~1,300 stars, Rust, by Roman Zeyde). Lightweight ~42 GB index for personal use. Fast initial sync (~1 day on a Raspberry Pi 4), but reparses blocks on the fly for deep wallet queries. v0.11.0 (Nov 2025).
• Blockstream/electrs (~372 stars). Esplora fork for enterprise. ~610 GB full index. Powers blockstream.info and mempool.space. HTTP REST API. Nadav Ivgi (shesek) and Blockstream.
• Fulcrum (~460 stars, C++). High-performance personal/enterprise server. Benchmarked at 22x faster wallet refresh than ElectrumX and ~300x faster than electrs for deep wallets. RocksDB. By Calin Culianu.

Electrum Personal Server (~900 stars, by Chris Belcher) was the lightweight single-user predecessor.

Block explorers

• mempool.space (~3,200 stars, TypeScript, by softsimon and mononaut). The de facto Bitcoin mempool visualizer. Real-time mempool, RBF Timeline, CPFP detection, Lightning Network explorer. Mempool-based fee estimation (analyzing current state rather than historical confirmations) inspired Core PR #34075 (December 2025), which introduces mempool-based fee estimation to Core itself. Self-hostable on Umbrel and RaspiBlitz.
• Esplora (~1,200 stars). Blockstream’s explorer (powers blockstream.info). 17 languages, light/dark themes.
• Blockbook (~600 stars, Go). Blockchain indexer by Trezor.

Compact block filters

BIP 157/158 compact block filters provide privacy-preserving sync. The server sends Golomb-coded set filters per block; the client checks locally without revealing addresses. BDK’s kyoto crate implements this for mobile wallets. Neutrino (LND’s BIP 157/158 light client, co-authored by Olaoluwa Osuntokun) was a critical milestone for self-custodial mobile wallets.

10. Layer 2 (Beyond Lightning)

In 2025 it stopped being accurate to treat Lightning as the only “Layer 2.” Four architectural families now coexist, each with distinct trust and exit-path assumptions, and the Bitcoin Layers framework evaluates them across BTC Custody, Data Availability, Network Operators, and Finality Guarantees.

Family	Exemplar	Properties
Channels	Lightning Network	Best-case unilateral exit, local data storage. ~6,000 BTC capacity.
Statechains	Spark (Lightspark), Mercury Layer	Statechain deposits can be unilaterally exited; safety depends on correct operator behavior after multiple hand-offs.
VTXO systems	Ark / Arkade (Ark Labs)	Pre-signed transactions, periodic rounds via ASPs. Exit guarantee depends on state management.
Rollups	Citrea, Alpen	Bitcoin as settlement/data layer for a ZK rollup. Validity proofs constrain fraud; practical withdrawals need an honest operator.

BitVM and ZK rollups

Robin Linus’s December 2023 BitVM paper demonstrated that arbitrary computation can be verified on Bitcoin using fraud proofs encoded into Taproot trees, requiring no consensus changes. The prover commits to a computation as a binary circuit; the verifier can challenge any gate; a dishonest prover is caught in O(log n) interactive rounds. BitVM1 was impractical (~1 GB on-chain dispute resolution), but BitVM2 (August 2024) achieved a single-round fraud proof using a split SNARK verifier, reducing the on-chain footprint to 2-4 MB and upgrading the trust model from honest majority to 1-of-N honest operator. Babylon’s mainnet test demonstrated a full BitVM2 dispute at ~$15,742 across 42 blocks.

BitVM3 (July 2025) applied garbled circuits (Yao’s 1986 technique) for a ~1000x improvement: assertion transactions of ~56 kB, disproval transactions of ~200 bytes, total dispute fees under $50, settlement in the next block using standard transactions. Computation moves off-chain (~280 GB data per challenger, ~5 TB per operator). The initial BitVM3-RSA variant was cryptographically broken by Liam Eagen at Fairgate Labs; the successor BitVM3s (secure, simple, Script-based) by Linus addresses these flaws, and Alpen Labs’ Glock (garbled lock) scheme further optimizes the circuit to ~12M gates. BitVM/BitVM (~488 stars) won the Bitcoin Research Prize 2025.

Citrea (Chainway Labs) builds the first ZK rollup on Bitcoin: thousands of transactions batched off-chain, zkEVM processing, validity proofs inscribed on Bitcoin as DA layer. The Clementine bridge uses BitVM2 for trust-minimized two-way pegs under a 1-of-N honest verifier assumption. Mainnet launched late 2025; native stablecoin (ctUSD) backed by Treasury bills. Alpen Labs (Strata) pursues a parallel approach, contributing Glock and targeting BitVM3-based bridges.

ZeroSync (~443 stars, Cairo). STARK proofs (Cairo language) for a proof of the entire Bitcoin chain state, enabling instant light client bootstrapping without downloading block data. Last updated November 2024; the team’s attention shifted significantly to BitVM.

Ark and Arkade

Burak Keceli’s Ark protocol introduces a fundamentally different off-chain architecture. An Ark Service Provider (ASP) coordinates periodic rounds in which multiple users co-sign transaction trees whose leaves are Virtual UTXOs (VTXOs), off-chain outputs that can be unilaterally exited to L1 by broadcasting the branch and leaf transactions using valid Taproot witnesses. Unlike Lightning channels, Ark requires no persistent bilateral relationship; payments occur within rounds by constructing new VTXO trees. VTXOs expire via absolute timelocks: users must refresh before expiry or the ASP reclaims liquidity.

Arkade (Ark Labs) launched in public beta on mainnet in October 2025, with batch settlement compressing thousands of operations into single Bitcoin transactions. SDKs ship in TypeScript, Go, and Rust, with launch partners including Breez, BTCPay Server, Boltz, and BlueWallet. Two main implementations exist: ark-network/ark (~91 stars, Go, by Second) and arkade-os/arkd (~128 stars, Go, by Ark Labs). The protocol works today without covenants (using pre-signed transactions) but would gain significant efficiency from OP_CTV or OP_CHECKSIGFROMSTACK.

Spark (Lightspark)

Lightspark (founded by David Marcus, former head of Facebook/Meta’s crypto efforts) had a banner 2025 with two flagship products: Spark (statechain-based L2 with FROST threshold signatures, alternative to Lightning for institutions not wanting custodial-Lightning regulatory overhead) and Grid (one API connecting traditional finance to Bitcoin via Lightning, compliance via Universal Money Addresses for Travel Rule, and connectivity across 65+ countries / 14,000 banks / 6 billion people).

Timeline:

Date	Development
May 29, 2025	Spark mainnet launch (self-custodial instant BTC + stablecoin transfers via statechains)
Aug 14	Tether integration: USDT on Spark via Wallet Developer Kit
Aug 19	SoFi partnership: 11M users, USD → BTC → fiat remittances
Oct 14	Acquired Striga for EU e-money license
Oct 17	Shakepay partnership (Canada)
Oct 22	Grid launch
Oct 23	Nubank pilot (100M+ users in LatAm)
Series A	$175M led by a16z

Spark introduces zero-cost internal transactions, forward fee transparency, offline receive capability, and LRC-20 token standard. Wallet of Satoshi and Breez SDK have integrated Spark support. Flashnet provides USDB-to-BTC swaps infrastructure on Spark.

Ecash: Fedimint and Cashu

Fedimint (~657 stars, Rust), created by Eric Sirion (Elsirion), implements federated Chaumian ecash. A federation of guardians runs AlephBFT consensus, issues blinded ecash notes backed by Bitcoin held in t-of-n threshold multisig, and redeems them, with the blinding ensuring guardians cannot link deposits to withdrawals. The trust model is “second-party custody”: users trust a small known group rather than a centralized third party. Lightning integration via gateway modules. Fedi (the company, CEO Obi Nwosu) builds consumer-facing products, and Fedimint landed on the Umbrel App Store in September 2025.

Cashu, created by Calle (@callebtc), takes the lighter-weight single-mint approach using Blind Diffie-Hellman Key Exchange. cashubtc/nuts defines the NUT specs. cashubtc/nutshell (~452 stars, Python) is the reference implementation; cashubtc/cdk is the Rust Development Kit. Implementations exist on iOS, Android, and PWA. Multinut payments (paying a single Lightning invoice from multiple mints) shipped in Q2 2025. ~32 public Cashu mints operate as of late 2025. Cashu’s simplicity enables rapid experimentation: Hashpool uses ecash tokens for accountless mining pool payouts; Routstr routes LLM API requests with per-request Cashu payments. Both Fedimint and Cashu provide perfect transaction privacy within the mint but require trust in the federation or mint operator for fund custody.

Sidechains and other layers

Liquid Network (ElementsProject/elements, ~1,000 stars), Blockstream’s federated sidechain on the Elements codebase. 15 functionaries in round-robin block signing (11-of-15 threshold), one-minute blocks, Confidential Transactions (Pedersen commitments hiding amounts, range proofs ensuring validity), and Issued Assets for tokenization. TVL ~$5 billion by end of 2025. Simplicity (~300 stars, Haskell/C), the formally-specified, stateless smart contract language by Russell O’Connor (Blockstream), launched on Liquid mainnet in July 2025.

Stacks (~3,000 stars, Rust). Smart contract layer using Proof of Transfer. The Nakamoto upgrade (Q4 2024) gave Stacks blocks Bitcoin finality; transactions become irreversible without reorging Bitcoin itself. sBTC, a decentralized BTC peg using an elected signer set (currently 14 signers including Blockdaemon, Kiln, Figment), enables BTC to move into Stacks’ Clarity smart contract environment, a decidable language with no unbounded loops, enabling formal verification.

RSK (Rootstock) (~700 stars). EVM-compatible Bitcoin sidechain using merge-mining.

RGB Protocol pushes smart contract state entirely off-chain via client-side validation: contract state lives with the asset holder, not on any shared ledger. Bitcoin UTXOs serve as Peter Todd’s “single-use seals”. The AluVM virtual machine provides Turing-complete execution in the client-side context. Dr. Maxim Orlovsky leads the LNP/BP Standards Association. RGB v0.12 (July 2025) was the production-readiness milestone, with native zk-STARK support for privacy and scalability. Tether announced plans to issue USDT on RGB.

DLCs (Discreet Log Contracts). Tadge Dryja’s 2017 proposal: oracle-attested conditional payments where the oracle signs an outcome using an adaptor signature scheme. The oracle does not know which contract uses its attestation, and with Taproot the on-chain footprint is indistinguishable from a standard multisig spend. Implementations include bitcoin-s (Suredbits), rust-dlc, and Nicolas Dorier’s NDLC (compatible with BTCPay Server). DLC Factories enable rolling contracts from a single funding transaction.

Sapio (~200 stars). Smart contract language for Bitcoin by Jeremy Rubin.

BOB (Build on Bitcoin). Hybrid L2: OP Stack + Bitcoin finality + EVM compatibility.

Babylon. Bitcoin staking protocol for securing PoS chains.

Drivechain (BIP 300/301). Paul Sztorc’s sidechain proposal using hashrate escrows. Highly debated.

Asset protocols on Bitcoin

Ordinals (~3,800 stars), the indexer and inscription tool by Casey Rodarmor, spawned the inscription wave. Runes (also Rodarmor, April 2024) brought a fungible token protocol on Bitcoin. BRC-20 (by “domo”) was the experimental token standard using Ordinals inscriptions. Alkanes is a new metaprotocol launched on Bitcoin in 2025 but failed to capture Runes-launch excitement. Runes, BRC-20s, and Ordinals all failed to sustain attention through 2025. Ordinals wallets and marketplaces include UniSat and Xverse.

Taproot Assets (formerly Taro) by Lightning Labs is the production system for issuing assets on Bitcoin and transferring them over Lightning. Used for DePix (stablecoin) and USDT distribution.

11. Mining

Pools

Pool	Notes
Foundry USA	~30% of hashrate. ~$100M annual revenue estimate. Pool fee ~2%.
F2Pool	Major global pool.
Antpool	Bitmain-affiliated.
Braiins	Formerly Slush Pool, the oldest. Now operates Braiins OS as firmware. Recently open-sourced BCB100 hardware design. Repos under braiins org.
OCEAN	Decentralized pool by Luke Dashjr and Jack Dorsey. Uses Stratum V2 and the DATUM protocol where miners construct and broadcast their own blocks. Non-custodial coinbase payouts.

Estimated industry-wide mining pool revenue is ~$289M annually.

Stratum V2

stratum-mining/stratum (~331 stars, Rust). Specification at sv2-spec (82 stars); application-level code at sv2-apps. Developed by Braiins (Jan Čapek, Pavel Moravec) and building on Matt Corallo’s BetterHash concept. SV2 introduces the Noise framework for end-to-end encryption, binary framing with ~30-70% bandwidth reduction, and the Job Negotiation Protocol allowing miners to run their own bitcoind and propose their own block templates, decentralizing transaction selection away from pools. ~15-20% of network hashrate used V2 by late 2025. Funded by Block via Fi3 and Rachel Rybarczyk.

Software

Project	Repo	Notes
CGMiner	ckolivas/cgminer	~4,600 stars. Classic Bitcoin/altcoin miner.
BFGMiner	luke-jr/bfgminer	~1,500 stars. Modular FPGA/ASIC miner by Luke Dashjr.
cpuminer	pooler/cpuminer	~1,200 stars. CPU-based, reference.
Public Pool	benjamin-wilson/public-pool	~390 stars. Self-hosted solo mining pool (NestJS). Zero fees. Popular with Bitaxe/home mining.
ckpool	ckolivas/ckpool	~300 stars. Ultra-low-overhead mining pool.

Hardware

Proto (Block subsidiary) launched “The Rig” in 2025, a modular open-source ASIC miner enabling on-rack repairs. US-manufactured. Bitmain dominates global ASIC supply, with Bitdeer, Bitfury, Canaan, and MicroBT as the other major OEMs.

Heat reuse and energy markets

Heat reuse applications include space heaters, water heaters, hot tubs, and industrial steam (21Energy, Heatbit, Sunbit, Exergy, Canaan).

Public miners (top by market cap)

Company	Ticker	Hashrate (EH/s)	BTC Held	Market Cap
Marathon	MARA	60.4	53,250	$3.88B
CleanSpark	CLSK	50.0	13,099	$3.16B
Iren	IREN	50.0	0	$15.08B
Bitdeer	BTDR	60.3	2,000	$2.71B
Riot	RIOT	38.5	18,005	$5.70B
Cipher	CIFR	23.6	1,500	$6.77B
Hut 8	HUT	1.8	13,696	$6.40B
Core Scientific	CORZ	19.1	2,116	$5.18B
Bitfarms	BITF	14.8	1,827	$1.70B
Terawulf	WULF	11.6	15	$5.46B

Public miners with AI partnerships (Iren, Cipher) commanded the highest valuation multiples in 2025 (22x and 33x TTM revenue respectively).

12. Merchant and Payment Infrastructure

BTCPay Server (~7,300 stars, C#), created by Nicolas Dorier and Andrew Camilleri (Kukks). Self-hosted, open-source Bitcoin payment processor. Runs its own bitcoind and Lightning node with an event-driven invoice engine backed by NBXplorer (a lightweight blockchain indexer tracking only registered derivation schemes). The Greenfield API (OpenAPI 3.0) exposes nearly every server function via REST with granular API key permissions, with official clients in C#, Python, Node.js, and PHP. Payments go directly to the merchant’s wallet: no third party holds funds, no fees beyond network costs, no KYC. The plugin system extends functionality for crowdfunding, point-of-sale, Shopify/WooCommerce integration, and payment splitting.

Galoy (~400 stars). Open-source “Banking-as-a-Service” with Lightning integration. Powers Blink (Bitcoin Beach wallet).

LNbits (covered above) is the canonical lightweight Lightning accounts platform.

Strike (Jack Mallers): Lightning-powered payments app, global remittances. $80M Series B in 2025.

Square / Block: Added Bitcoin payments to all Square POS terminals in 2025. Steak and Shake launched Bitcoin payments at all locations, with 15% same-store sales increase. Cash App holds significant BTC for users.

Castle (Epoch portfolio): Connects fragmented POS market to Bitcoin. Zaprite: Standard payment and accounting with native Bitcoin support. Voltage: Lightning infrastructure-as-a-service. Amboss: Lightning Network data and analytics. Synota: Lightning-based energy payment settlements. Musqet, Opago, Tando: Bitcoin POS.

Onramps and offramps: Bringin, Aureo. Remittances: Strike, Crobo, NeutronPay, Osmo, Guap. eCommerce: Zaprite, Flash, OpenNode. Personal finance: Fold, Azteco, BitRefill, Oshi.

13. Self-Hosted Node Distributions

Project	Stars	Notes
Umbrel	~7,500	Docker Compose app store, polished web UI. $434 dedicated hardware.
RaspiBlitz	~2,400	Christian Rotzoll’s Raspberry Pi-focused system with LCD, CLI-driven. MIT-licensed.
Start9 (StartOS)	~700	Self-sovereign server OS. Built-in Tor, btrfs. Most privacy-focused.
myNode	~600	Easy full node device and software.
Polar	~700	One-click LN dev environment.
Nodl	-	Bitcoin and Lightning full node hardware.

These platforms collectively turned “run a full node + LN + Electrum server + explorer” from a multi-day Linux administration project into a one-click afternoon.

14. Nostr

Project	Stars	Notes
nostr-protocol/nostr	~11,150	Main protocol spec. Created by fiatjaf (André Medeiros, Brazilian). “Notes and Other Stuff Transmitted by Relays.”
nostr-protocol/nips	~2,860	Implementation Possibilities (standards docs). 385 contributors.
Damus	~2,100	iOS Nostr client by Will Casarin (jb55). First Nostr app on the App Store (Feb 2023). Zaps, Damus Purple.
Amethyst	~1,300	Android Nostr client by Vitor Pamplona. Jetpack Compose. Quartz KMP library.
Primal	-	Nostr client with Bitcoin wallet integration.
Alby	~400	Browser extension Lightning wallet plus Nostr.

Bitchat is Jack Dorsey’s “vibe-coded” Bluetooth mesh P2P communication app with Cashu integration (by Calle). It saw 50,000 downloads during Nepal protests on September 8 alone, hundreds of thousands total. Heavy 2025 funding flowed from Spiral, OpenSats, and Maelstrom into Nostr.

15. The Funding Landscape

Annual Bitcoin Core development spending sits under $10M, a small fraction of what comparable-value networks spend. The 13 main organizations supporting Bitcoin development in late 2025:

Org	Model	Notes
Chaincode Labs	Employment	NYC-based R&D center, largest single funder (46% of employment spending in 2023). Employs Pieter Wuille, Suhas Daftuar, Murch, Martin Zumsande. Founded by Alex Morcos and Suhas Daftuar. Runs the BOSS Challenge, the Chaincode Residency, and seminars.
Blockstream	Employment	Builds Liquid sidechain, Core Lightning, Elements, Greenlight, Jade hardware, satellite network. Employs Ava Chow, Andrew Poelstra, Rusty Russell. Founded by Adam Back (2014).
Spiral	Grants	Independent Bitcoin dev unit under Block. Led by Steve Lee. Funded 100+ open-source projects including LDK (Matt Corallo). Builds LDK and contributes to BDK.
Lightning Labs	Employment	LND, Loop, Pool, Taproot Assets. Founded by Elizabeth Stark and Olaoluwa Osuntokun.
MIT Digital Currency Initiative (DCI)	Research	MIT Media Lab. Employs Cory Fields, Neha Narula (director), Tadge Dryja (Lightning co-inventor).
Brink	Grants and fellowships	Founded 2020 by John Newbery. 100% donation-funded. Commissioned the first public Core security audit (Quarkslab, Nov 2025). Donors include Jack Dorsey, Chaincode, HRF, Gemini, Kraken.
OpenSats	Grants and LTS	~$30M to 330+ contributors across 40+ countries. ~295 grants. LTS grant program for core developers.
Human Rights Foundation (HRF)	Grants	Alex Gladstein leads Bitcoin program. Funds privacy, censorship resistance, human rights tooling.
Btrust	Grants and training	Founded 2021 by Jack Dorsey and Jay-Z (500 BTC endowment). Lagos-based. Trained hundreds of African and Indian developers. Absorbed Qala. Interim CEO Abubakar Nur Khalil.
Vinteum	Grants and training	Founded August 2022 by Lucas Ferreira, Bruno Garcia, André Neves. Brazil and Latin America. 20+ developers funded as of August 2025 (3rd anniversary).
Maelstrom	Grants and VC	Arthur Hayes (BitMEX co-founder). “Bitcoin Moonshot Grants” for radical innovation. ~$20-30M deployed. Also supports Nostr and Fedimint.
B4OS / Librería de Satoshi	Training	Free advanced Bitcoin training for Spanish-speaking developers. CEO Dulce Villarreal. 3-year LTS grant from Btrust in 2025.
2140	Grants	European Bitcoin developer funding.

Exchanges supporting development: OKX (the only exchange among 13 core sponsors, ~$2M in grants to Marco Falke, Amiti Uttarwar, Antoine Riard, Brink, Vinteum), Kraken, Gemini, Bitfinex, and historically BitMEX.

Geographic distribution of the ~41 active Core developers: 26 in US/Europe, 3 in Latin America, 4 in Africa/Asia/Australia/Canada. Concentration risk is real: top three funding organizations each depend on a single source for over 62% of aggregate funding.

16. Education and Onboarding

Program	Org	Notes
BOSS Challenge	Chaincode	3-month structured program. Alumni funded by Spiral, OpenSats, Brink, Maelstrom, Btrust, Blockstream.
Chaincode Residency	Chaincode	In-person NYC Bitcoin/Lightning protocol residency since 2016.
Chaincode Seminars	Chaincode	Online curriculum with reading and discussion. Free.
Btrust Builders Fellowship	Btrust	Training for African developers (absorbed Qala).
B4OS	Librería de Satoshi	Free 6-month technical training for senior devs in LatAm/Caribbean/Spain. First international B4OS residency: Florianópolis, Brazil, Feb-Mar 2026 (2-week immersive).
Summer of Bitcoin	Adi Shankara	Google Summer of Code-style.
Scalar School	Founders L. Ferreira and R. Rybarczyk	Brazilian Portuguese curriculum. HRF-funded. Covered in Brazilian section.
bitcoin++	Various	Developer-focused conferences.
TabConf	Community	Atlanta. Hands-on workshops. Longest-running developer conference.
Base58	Community	Advanced protocol education and workshops.
Bitcoin Optech	Brink + Optech	Weekly newsletter and workshops. Run by Mike Schmidt.
Bitcoin Dev Mailing List	-	Google Groups. Primary venue for protocol-level discussion.
Delving Bitcoin	-	Forum for technical discussions.
PlebDev	Community	Beginner-to-intermediate courses.
BitDevs Meetups	Global	Monthly Socratic Seminars in NYC, SF, London, Lagos, Austin, and more.
Bitcoin Design Guide	~500 stars	Open-source design guide for Bitcoin products.
Mastering Bitcoin	~23,000 stars	Antonopoulos’s canonical book.
Mastering the Lightning Network	~3,000 stars	Antonopoulos, Osuntokun, Pickhardt.
Programming Bitcoin	~1,830 stars	Jimmy Song, O’Reilly.
Learning Bitcoin from CLI	~3,300 stars	Christopher Allen.

17. Business and VC Landscape

Bitcoin-only VC funds (15 firms, ~20 funds total)

Ten31, Ego Death Capital, Axiom, Epoch, Cantilever Advisors, Hivemind, Timechain (Concentric), UTXO Management, Sats Ventures, Fulgur Ventures, Plan B, Lightning Ventures, Recursive Capital, Trammel Ventures, Bitcoin Opportunity Fund.

Bitcoin VC has collectively raised less than $1B (vs$85B+ for crypto VC overall). Average Bitcoin VC fund size: ~$20M (vs ~$98M for crypto VC). Bitcoin companies account for ~7% of crypto venture deal count, ~4% of total venture investment. Bitcoin deal count grew ~40% YoY in 2025. Median seed-stage Bitcoin VC valuation: $15-20M (vs$25M for crypto VC). Less than 10% of funded Bitcoin companies have outright failed (vs >50% typical for traditional VC). ~225 Bitcoin companies have received venture funding to date; 90% founded and funded post-2021.

Notable 2025 raises

Company	Raise	Lead
Lightspark	$175M Series A	a16z
Meanwhile	$82M (Bitcoin life insurance)	Bain Capital Crypto, Haun Ventures
Strike	$80M Series B	Ten31
Unchained	$60M Series B	Valor Equity Partners
River	$35M Series B	Kingsway, Peter Thiel, Valor
Lava Finance	$17.5M	Khosla, Founders Fund
Relai	$12M Series A	Ego Death Capital
Bipa	~$4.53M total	New Form Capital, Hivemind, Ego Death Capital, others

Emerging business models (Epoch 2026 framework)

• AI + Bitcoin mining: Few public miners pivoted, but those announcing AI partnerships (Iren, Cipher) saw the highest valuation multiples.
• Bitcoin-collateralized bank lending: With SAB 121 repealed, BNY Mellon, State Street, Deutsche Bank, SoFi entered Bitcoin custody. Cantor Fitzgerald launched a $2B collateralized lending program. New Thiel-backed bank Erebor specifically targets Bitcoin/crypto-native banking.
• Correspondent banking on Lightning (“deCentral Banking”): Lightspark Grid enabling traditional banks to use Bitcoin/Lightning as settlement rails. Used by SoFi and Nubank.
• Square Bitcoin payments at all POS: Arguably the biggest merchant adoption event in Bitcoin history.
• Bitcoin reserve stablecoins: Interest-bearing stablecoins using Bitcoin as reserve asset, expected offshore given GENIUS Act restrictions.
• Proto (Block subsidiary): “The Rig” modular open-source ASIC, US-manufactured.
• Heat reuse mining: Space heaters, water heaters, hot tubs (21Energy, Heatbit, Sunbit, Exergy).

Adjacent companies of note

P2P exchanges: Bisq (~4,700 stars), RoboSats (~600), Peach Bitcoin, HodlHodl, Debifi.

Custody and shared custody: Casa (CTO Jameson Lopp), Unchained, Theya, Anchorage, BitGo, Fidelity Digital Assets, Gemini, BNY Mellon, Magnolia Financial.

Lending: Ledn, Nexo, Lava Finance, Firefish (3,000 BTC collateral locked, 25,000+ users in 2025), Debifi.

Insurance: Meanwhile (life), Anchorwatch (custodial risk).

Markets: Luxor, Roxom (hashrate derivatives), LN Markets.

Trading libraries: CCXT (~33,000 stars, 100+ exchanges), Freqtrade (~34,000 stars, open-source crypto trading bot).

Other notable Bitcoin-adjacent projects: OpenTimestamps (~500 stars, Peter Todd), Sphinx Chat (~400, chat on Lightning), Lightning Address (~300), Boltz (~200, non-custodial BTC ↔ LN swaps), PeerSwap (~200, channel rebalancing via atomic swaps).

Cultural and media

BTC Inc. (Bitcoin Magazine, major events, $100M+ revenue), What Bitcoin Did (relaunched podcast by Danny Knowles), Coin Stories, TFTC, Fountain (podcast app with LN), Geyser (Bitcoin crowdfunding), Orange Pill App.

Public Bitcoin balance sheets

The MicroStrategy / Strategy (Michael Saylor) playbook expanded. In Brazil, Méliuz (CASH3) became the first publicly traded Bitcoin Treasury Company there in May 2025, holding 604.69 BTC (#1 in Latin America among listed companies, #36 globally). OranjeBTC bought ~$385M of BTC in September 2025 and plans a B3 listing via reverse merger. Tahini’s, Metaplanet, Nakamoto, Steak and Shake all became balance-sheet adopters.

Regulatory milestones (2025)

• SAB 121 repealed (early 2025): banks can custody crypto without balance sheet liabilities.
• GENIUS Act passed: first major federal crypto legislation (stablecoins).
• CLARITY Act (market structure): House-passed July 2025 (294-134), Senate markup ongoing. Section 109 protects developers.
• OCC: approved 5 National Trust Bank Charters to digital asset institutions.
• SEC: in-kind redemption for Bitcoin ETFs, crypto custody rules for broker-dealers.
• CFTC: permitted BTC, ETH, USDC as collateral in derivatives contexts.
• Bitcoin ETFs added ~250,000 BTC in 2025 (led by BlackRock IBIT).
• cbBTC (Coinbase wrapped BTC) grew from 17,460 to 77,512 BTC across Ethereum, Base, Solana.

18. The Brazilian Ecosystem

Brazil has become one of the most consequential non-US/EU hubs of Bitcoin development, with a distinct funding org (Vinteum), a distinct educational pipeline (Scalar School and B4OS), a Lightning-native stablecoin (DePix), and one of the most active Lightning user bases in the world (the country accounts for 30% of ZEBEDEE activity).

Vinteum

Non-profit Bitcoin R&D center for Brazil and Latin America, founded August 10, 2022. Founders: Lucas Ferreira (lucasdcf) (Executive Director, Lightning Labs BD), André Neves (Director of Partnerships, ZEBEDEE CTO), Bruno Garcia (Director of Education, Bitcoin Core contributor).

Donors: John Pfeffer (Pfeffer Capital), Wences Casares (Xapo Bank), Sebastian Serrano (Ripio CEO), Okcoin, HRF. In-kind: Casa, Voltage. 20+ developers funded as of August 2025 (3rd anniversary). Named grantees include Bruno Garcia (#1, August 2022), Davidson Souza (#2, November 2022), and Níckolas Goline. Developers work on Bitcoin Core, LND, Utreexo, BDK, Stratum V2, Floresta, Bitcoinfuzz, Rust Bitcoin.

The educational program was directly modeled on the Chaincode Labs seminar curriculum, translated to Portuguese. Lucas Ferreira had placed seven Brazilians into Chaincode programs before founding Vinteum. Program structure: quarterly online seminars in Portuguese; “Bitcoin Dev Launchpad” intensive (2nd batch upcoming); weekly seminars; physical hacker houses; community events in Brazilian cities. Planned: Bitcoin Dev Summit, DIY Hardware Wallet Retreat, Floresta Developer Retreat. The Vinteum GitHub org is at vinteumorg and includes pleblottery, a Rust-based hashrate aggregator for solo mining over Stratum V2.

Key Brazilian developers

Name	Handle	Work
fiatjaf (André Medeiros)	@fiatjaf	Nostr protocol creator, LNURL, Lightning Address, LNTXBOT. 2,300+ GitHub followers.
Bruno Garcia	@brunoerg	Bitcoin Core (P2P, Wallet, REST API, test coverage). Reviewed Taproot. Vinteum Director of Education; formerly Brink grantee.
Davidson Souza	@Davidson-Souza	Utreexo (Rust), Floresta. Vinteum grantee #2 (Nov 2022).
Lucas Ferreira	@lucasdcf	Vinteum co-founder, Satsconf co-founder, Lightning Labs BD.
André Neves	-	ZEBEDEE co-founder, Vinteum co-founder, NBD (Nostr).
Luciana Ferreira	@biohazel	Scalar School co-founder. Translated “Mastering the Lightning Network” to Portuguese. WalletScrutiny contributor.
Rachel Rybarczyk	@rrybarczyk	Stratum V2 protocol developer (6+ years in mining). Scalar School co-founder.
Níckolas Goline	-	Vinteum grantee/fellow.
Luiz Parreira	-	Bipa founder/CEO (first Brazilian Lightning app).
Eduardo Jatahy	-	DePix stablecoin, Plebank/Eulen.
Rodrigo Souza	-	BlinkTrade founder (exchanges in Vietnam, Pakistan, Venezuela, Brazil).
Raphael Zagury	-	Elektron Energy (large-scale mining), Nakamoto Portfolio.

Of the ~41 active Bitcoin Core developers tracked in 2024, 3 were in Latin America (Argentina, Brazil, El Salvador).

fiatjaf (deep profile)

Born 1991, southeastern Brazil. The nickname comes from a school trip to a Fiat car factory: he got a Fiat-logo hat, combined “Fiat” with the old nickname “JAF.” Economics degree from a Brazilian university (early 2010s), interested in Austrian economics. Entered Bitcoin in 2011: “I mined for an entire night, and I got 5,000 Satoshis.”

The Nostr protocol was first written in 2020 as a response to Twitter moderation issues and disagreements with ActivityPub and Secure Scuttlebutt. The name expands to “Notes and Other Stuff Transmitted by Relays.” It hit a turning point in early 2023 when Damus launched on the App Store. Jack Dorsey support went from ~$250K initially to$5M+ to Nostr developers ($10M total donations reported in 2025). The network has ~18 million registered users.

Other fiatjaf projects: LNURL suite (lnurl-pay, lnurl-withdraw, lnurl-auth), Lightning Address, LNTXBOT (Telegram), nostr-tools, nak, Etleneum, go-lnurl, lightningd-gjson-rpc. He worked at ZEBEDEE for a stretch.

Scalar School

Founded at Bitcoin block 834,812 (~April 2024) by Luciana Ferreira and Rachel Rybarczyk, funded by an HRF grant. Curriculum: BDEV101 “Fundamentos do Bitcoin”, a 3-night course covering Bitcoin fundamentals, human rights / women’s rights relevance, safe storage, transaction execution and verification, and a Bitcoin Script intro. Certificate issued. Free (HRF-funded). Based on Base58, Chaincode Labs, Bitshala, UNIC, and O’Reilly’s “Mastering” books.

All materials are MIT-licensed and produced in Brazilian Portuguese. The target audience is women developers and tech students, but the Discord is open to all genders. Beyond courses: Bitcoin Students Network (Fatec Bitcoin Club, UFSCar Bitcoin Club), Bitdevs Interior events in Ribeirão Preto and São Carlos, and the Scalar School Handbook on GitHub.

Background of the founders: Luciana Ferreira has been in FinTech since 2021 (built AI assistants for Itaú, Bradesco, BMG), Bitcoin FOSS dev since 2022, participated in Chaincode Labs and Base58 programs, organized SatsHack 2023, formerly Vinteum Director of Programs. Rachel Rybarczyk has been in Bitcoin mining 6+ years, designing custom mining management and energy systems, and contributes to Stratum V2.

Super Testnet on Scalar’s role: “Without the support of Scalar School, many potential developers might not find a place to learn how to make bitcoin apps.”

B4OS

B4OS is a free 6-month technical training program for senior developers interested in Bitcoin Core and Lightning FOSS development, run by Librería de Satoshi (CEO Dulce Villarreal). Open to developers from Latin America, the Caribbean, and Spain. Structure: async programming challenges (Proof of Work) on Discord, selection, 5 months of online seminars + working groups + Bitdevs + meetups, then a 2-week in-person immersive residency. The first international B4OS residency is Florianópolis, Brazil, February-March 2026.

Predecessor: BOSS (Bitcoin Open Source Software), a Chaincode + Librería de Satoshi initiative. 2025 program: registration closed September 15, selection October 20, online phase October 30, 2025 to February 2026. Awards include a $300 "Rookie" prize. Outcomes: 2024 alumni obtained grants from Spiral and the BDK Foundation; some got full-time Bitcoin jobs. Micro-grants to 21 developers + 5 educators + 3 UI/UX designers. Btrust awarded B4OS / Librería de Satoshi a 3-year LTS grant in 2025 as part of$1M+ across 10 initiatives.

DePix and Lightning adoption

DePix is a BRL-pegged stablecoin (1:1 with the Brazilian Real) on the Liquid Network and as a Taproot Asset on Lightning. Users send Pix payments, receive DePix tokens, and can swap for BTC (L-BTC) on SideSwap. Calling it the “Transient Tactful Token (3T)” reflects that it is intended as a temporary fiat-to-Bitcoin intermediary, not a hold asset. Privacy via Liquid’s confidential transactions. First stablecoin issued as a Taproot Asset on Lightning. Builder: Eulen, founded by Eduardo Jatahy (CEO of Plebank). Partnership with Joltz, the world’s first non-custodial wallet/SDK supporting Taproot Assets. The BTCPay Server plugin (with Vinteum support by Thgoo) lets merchants accept Pix and settle in DePix. GitHub: eulen-repo/DePix.

Bipa is a Brazilian mobile fintech for buying/selling/holding BTC and USDT using Pix and Lightning. Founded 2020 by Luiz Parreira (CEO), São Paulo. First Brazilian app to integrate Lightning. Features include buying BTC from R$1 via Pix, Lightning deposits/withdrawals, a "BitPix" key (receive Pix directly in BTC or USDT), and a virtual debit card via Google Pay.$1.4M seed (July 2023) from New Form Capital and Hivemind, $4.53M total from 9 investors including Ego Death Capital, Initial Capital, Timechain UK. ~49 employees. ZEBEDEE integration (March 2022) gave a Lightning off-ramp for Brazilian gaming rewards.

ZEBEDEE: Brazil = 30% of total activity despite only 9% of accounts. Brazilian gamers dominate the top 100 leaderboard on ZBD Infuse (Counter-Strike with Bitcoin). Pix context: 93% of Brazilian adults use Pix, 37.4 billion transactions in 2023, ~R$2.5T/month. Azteco Bitcoin vouchers are purchasable with Pix at 125,000+ locations in Brazil. Bitget Wallet, KuCoin Pay, Binance Pay, and Bybit Pay all integrated Pix for crypto in 2025. Brazil has a 20.6% crypto adoption rate (#2 globally after Turkey at 25.6%).

Exchanges

Mercado Bitcoin. Founded 2013 by brothers Gustavo and Mauricio Chamati. Largest crypto exchange in Brazil and Latin America by trading volume. 3.7M+ customers, $50B+ cumulative volume, ~500 employees. Owned by 2TM Group; CEO Roberto Dagnoni. July 2021:$200M Series B from SoftBank Latin America Fund, valuing 2TM at $2.1B (first Latin American crypto unicorn). Nov 2021:$50.3M additional from 10T, Tribe Capital. 2TM subsidiaries: Mercado Bitcoin, MB Tokens, MB Asset, MB One (institutional), Bitrust (custody), Blockchain Academy, Portal do Bitcoin (news), Criptoloja / MB Portugal. Received a payment institution license from the Central Bank (BCB) in late 2024/2025; can operate as electronic money issuer. Planning MB Pay digital banking. Multi-crypto (BTC, ETH, SOL, ADA, DOGE, LTC, stablecoins, NFTs, RWA tokens).

Foxbit. Founded October 2014 by João Canhada (CEO) and Luís Augusto Schiavon Ramos (“Guto Schiavon”), Osasco, São Paulo. One of Brazil’s oldest exchanges. Member of BlinkTrade network. 2016: acquired BitInvest payment processor, held ~55% of Brazilian Bitcoin market. 2021: expanded to B2B/B2B2C with tokenization. **February 2022: $20M Series A led by OK Group (OKX)**. ~1M registered customers, R$20B+ cumulative traded, ~106 employees. Multi-crypto: 100+ cryptocurrencies including BTC, ETH, LTC, XRP, USDT.

Regulation

Law 14.478/2022 (Virtual Assets Law): Enacted December 21, 2022 (Bolsonaro); effective June 20, 2023. Defines “virtual asset” as digital representation of value tradable electronically. Excludes NFTs, tokenized securities, electronic currency, loyalty tokens. Mandates VASPs obtain federal authorization (delegated to BCB). Amends Criminal Code to add “fraud with virtual assets.” Amends AML law (9,613/1998) to include VASPs. Preserves CVM authority over security tokens.

BCB Resolutions (November 2025), effective February 2, 2026: Resolution 519/2025 (VASP authorization process), 520/2025 (operational rules including AML/CTF and Travel Rule), 521/2025 (foreign exchange rules, classifies stablecoins as FX operations). Travel Rule implementation in two stages: 2026-2028.

Brazil received **$318.8 billion in crypto value** mid-2024 to mid-2025, 109.9$1.7T in on-chain volume mid-2024 to mid-2025.

Taxation: 15-22.5% capital gains. Monthly gains under BRL 35,000 tax-exempt. Provisional Measure 1,303/2025 proposes a flat 17.5% and removing the exemption (under Congressional review). DeCripto reporting system launching July 2026 (OECD CARF aligned). 0% import duty on SHA-256 mining hardware (>200 TH/s, <20 J/TH) extended through January 2028 (GECEX Resolution 861). 0% duty on hardware wallets through December 2025.

DREX (Digital Real CBDC): Named August 7, 2023. Pilot Phase 1 (2023-2024) on Hyperledger Besu. Phase 2 (2024-2025): 16 consortia (Visa, Santander, Mastercard, Microsoft). Major pivot fall 2025: BCB shut down the blockchain-based platform due to “high maintenance costs and unresolved privacy issues.” Pivoted to a lien reconciliation system without blockchain initially. Phase 3 planned 2026; public launch targeted first half 2026 (phased).

Other regulatory milestones: Binance secured a broker license. Brazil launched the first spot XRP ETF globally (XRPH11 by Hashdex, April 2025), already had approved spot Bitcoin and Ethereum ETFs ahead of the US. Bill PL 957/2025 is debating allowing partial salary payments in crypto.

Mining

GECEX Resolution 861 (February 2025): 0% import duty on high-efficiency SHA-256 miners (>200 TH/s, <20 J/TH) through January 2028.

Energy opportunity: Brazil’s wind + solar generated 24% of electricity in 2024, hitting 34% in August 2025. Between October 2021 and September 2025, Brazil’s wind industry suffered 32 TWh in curtailment (energy produced but not fed to grid), estimated loss R$6 billion (~$1.2 billion). In 2025, ~1/5th of solar/wind generation was curtailed, wasting R$6.5 billion ($1.23 billion). Bitcoin mining break-even sits around $0.071/kWh (~R$370/MWh). Retail rates are too high, but wholesale spot (R$250-450/MWh) and curtailed energy (effectively zero cost) open a profitability window.

Major developments:

• Engie (French state-owned utility): evaluating BTC mining at its Assu Sol solar plant (895 MW) in northeast Brazil, its largest solar facility globally. Would monetize curtailed electricity. “Would take years to implement.”
• Tether + Adecoagro (announced July 3, 2025): MoU for renewable energy-powered BTC mining in Brazil. Adecoagro (NYSE: AGRO, 70% owned by Tether) is a major food producer with significant power generation. Will use Tether’s Mining OS. Tether CEO Ardoino aims to be “biggest bitcoin miner by end of year” with $2B invested.
• Vextron Tecnologia: Brazilian mining company, mining since 2018, large-scale operations, working with the energy market since 2020. Co-founder spoke at Satsconf 2025.
• Elektron Energy: founded by Raphael Zagury, US-based large-scale Bitcoin mining. Created Nakamoto Portfolio.

Notable Brazilian Bitcoin companies (2024-2025)

Company	Type	Key Data
Méliuz (CASH3)	First publicly traded Bitcoin Treasury Company in Brazil (May 2025)	Holds 604.69 BTC (avg cost $103,323). Stock up ~160% YTD. 30M+ registered users. Head of BTC Strategy: Diego Kolling. CEO: Israel Salmen. #1 BTC holder among listed companies in Latin America, #36 globally.
OranjeBTC	Bitcoin treasury company	~$385M BTC purchase (Sept 2025), plans B3 listing via reverse merger.$400M+ in BTC. Ranked #27 worldwide in BTC treasuries.
Hashdex	Crypto asset manager	Created multiple crypto ETFs on B3 including XRPH11 (spot XRP, first globally), GBTC11.
CloudWalk	Payments + blockchain	$365M funding,$320M revenue (2023), 1M+ customers, 5,500 cities. Expanded to US 2024.
EBANX	Payment platform (LatAm)	$460M total funding. Connects global companies to LatAm.
Stark Bank	Online business bank	Serves 52 crypto/blockchain firms. Processed 155B reais ($27B) in payments (2023).
QR Capital	Blockchain investment	Builds/invests in blockchain ecosystem companies in Brazil.
Brasil Bitcoin	Crypto exchange	P2P technology focused exchange.

Aggregate: Brazilian fintech sector secured $1B in VC funding in 2024 (42% of all LatAm fintech investment).

Community: cities, conferences, meetups

Key cities:

• São Paulo: primary hub. HQ of Mercado Bitcoin, Méliuz, most exchanges. Hosts Satsconf, Blockchain Conference Brasil, DAC, Bitcoin São Paulo Meetup.
• Florianópolis: developer-focused hub. Hosts bitcoin++ Floripa (hackathon), B4OS residencies. Known as a tech/startup city.
• Rio de Janeiro: hosts Blockchain Rio conference (August 5-7, 2025).
• Belo Horizonte: active Bitdevs meetup.
• Ribeirão Preto and São Carlos (SP interior): host Bitdevs Interior organized by Scalar School.

Major conferences:

1. Satsconf (São Paulo): Brazil’s largest 100% Bitcoin-only conference. Founded by Lucas Ferreira. 2024: November 8-9, Audio venue. 2025 confirmed. Speakers: Diego Kolling (Méliuz), Alan Schramm, Bernardo Braga, Raphael Zagury.
2. Blockchain Conference Brasil (São Paulo): formerly “BitSampa” (est. 2019). Largest overall blockchain event. November 28-29, 2025, Expo Center Norte. 10,000+ attendees, 200+ exhibitors. Sold out every edition.
3. bitcoin++ Floripa (Florianópolis): developer hackathon, February 19-22, 2025, ACATE Centro de Inovação. 10M+ sats in prizes.
4. Digital Assets Conference (DAC) Brazil 2025: by Mercado Bitcoin, September 22-23, Teatro B32, SP. Institutional focus. Partners: BlackRock, CME Group, Fireblocks, Galaxy Digital, Tether.
5. Blockchain Rio: Rio de Janeiro, August 5-7, 2025.

Meetup culture: Bitcoin São Paulo Meetup (Meetup.com), Bitdevs Interior (Scalar School), Bitdevs BH, university Bitcoin clubs (Fatec, UFSCar), “Blockchain on the Road” university tour (Francisco Carvalho / Blockchain Rio, visited UnB in 2025).

Additional notable entities

• Bitcoin Beach Brazil (Praia Bitcoin): Social project in Jericoacoara, Ceará, founded by Fernando Motolese. Teaching children to use Bitcoin at school.
• ZEBEDEE: Bitcoin gaming fintech co-founded by Brazilian André Neves. Brazil = 30% of activity. Product of Chaincode Labs’ first Lightning Residency (2018).
• Paradigma: First Brazilian crypto research company. Co-founded by Felipe, author of “Um Café com Satoshi” (first book with an embedded wallet).
• BitNada: Leading Portuguese-language YouTube channel on Bitcoin.
• Educação Real: Founded by Alan Schramm (co-author “Bitcoin Red Pill” bestseller, author “O Mínimo sobre Bitcoin”), co-founder/CEO of Satsails.
• BetterMoney: Founded by Bernardo Braga. Bitcoin education and consulting for sovereignty/self-custody.
• FGV (Fundação Getúlio Vargas): Launched South America’s first Master’s degree in crypto-finance (2018). Coordinator: Ricardo Rochman.
• UniFECAF: Brazil’s first postgraduate course in blockchain development. 100% online, 360 hours, MEC-certified. Partnership with BlockTrends.
• Wences Casares: Argentine-born but deep Brazilian connection (founded Banco Lemon in Brazil, acquired by Banco do Brasil in 2009). Xapo Bank founder. Known as “Patient Zero” for Bitcoin adoption in Silicon Valley. Vinteum sponsor.

19. Where the Foundation Stands

The technical layer is the strongest it has been since Taproot. Cluster Mempool finally aligns mining incentives with eviction policy after years of research. The Miniscript-Descriptor-PSBT stack is genuinely interoperable. FROST and MuSig2 are production-quality. TRUC and Package Relay closed Lightning’s biggest pinning vector. BitVM2 and BitVM3 turned “fraud-proof bridges on Bitcoin” from a paper into mainnet code.

The human layer is more fragile. Five maintainers for a $1.7T network. Under$10M in annual spending. A governance crisis over OP_RETURN that cost the project Gloria Zhao. Concentration risk: Chaincode contributes ~46% of employment spending, and the top three funding orgs each depend on a single source for 62%+ of aggregate funding. Geographic centralization: 26 of the 41 active developers in US/Europe.

The on-ramps are well-paved. BDK with descriptor wallets is a production-ready framework. The Bitcoin Core PR Review Club is structured learning. Brink, OpenSats, Chaincode’s BOSS Challenge, Vinteum, Btrust, B4OS, and Scalar School cover funding and mentorship in nearly every region that wants them. The technical work that needs more people: quantum-resistant signatures (BIP 360), activating covenant opcodes, scaling Lightning with PTLCs and LN-Symmetry, cluster-mempool follow-up. The code is there. What the foundation needs most is more people reading it.

Sources and further reading

• BIPs / bips.dev / Delving Bitcoin / Bitcoin Dev mailing list
• Bitcoin Optech weekly newsletter
• Bitcoin Core PR Review Club
• Bitcoin Layers framework
• Jameson Lopp’s annual Bitcoin Core statistics (blog.lopp.net)
• Epoch Management, “The Bitcoin Ecosystem 2026 Annual Report” (January 21, 2026), by Eric Yakes, VJ Vesnaver, Adam Stryer, Fernando Nikolić, Red Sheehan (Taproot Wizards), Brendan Quinn (Cantilever Advisors), and Jon Frisch (Cantilever Advisors)
• Christine Kim, “Bitcoin Contributor Directory”
• Jameson Lopp, “Who Controls Bitcoin Core?”
• Mastering Bitcoin and Mastering the Lightning Network (Antonopoulos et al.)
• awesome-bitcoin, awesome-btcdev, awesome-lightning-network, awesome-bdk, best-of-crypto