Three Projects, Three Theses
Three implementations active in the 2025–26 alt-client wave — different theses, different stages
PRODUCTIONREADY
SOCIAL-DYNAMICS PITCH
The ProductionReady client (Song · Mow · Lewis · Ratcliff), pitched in Song's voice as "conservative", "no drama", "we listen". Thesis: "3+ implementations create entirely different social dynamics."
LIBBITCOIN
PERFORMANCE / MODULARITY
Eric Voskuil's long-running C++ stack. v4 in development — in-memory metadata graph for block-template production, swappable storage, decoupled components.
HORNET
FORMAL-SPEC PITCH
Toby Sharp's clean-slate C++ effort. Aims to extract consensus into a precise, executable specification. Paper out Sep 2025; code not released yet.
CONTEXT
All three sit in the 2025–26 alt-client wave alongside Knots. Song's promo post is the public-facing pitch for the ProductionReady implementation — same project, different voice.
LIBBITCOIN — WHERE V4 ACTUALLY IS
Voskuil signalled v4 would "mature around the end of 2025" with a "functional preview in early 2026". As of May 2026 the latest tagged release of
libbitcoin-node is still v3.8.0 — v4 has not shipped. Active dev continued into Jan 2026 (system-dep alignment, build improvements). v4 design notes still call out a connection layer for Sparrow (via ElectrumX) and Stratum V1 (via JSON-RPC), and tx protocols slated for after the initial release alongside mining support.ProductionReady Launch & Early Criticism
Song's launch promo for the ProductionReady client and the community reaction to it
"The nice part about the Luke ratio of the new Jimmy Song client promo post is that it immediately lays bare the hand-waving of 'conservative', 'no drama' and 'we listen and engage and get feedback from Bitcoiners' all at once. Turns out, other people already think the decisions are the opposite of conservative, they inject high drama, and then Jimmy doesn't engage on the community's feedback. I guess 'Three or more implementations create entirely different social dynamics' isn't quite true either."
— from the May Perth BitDevs issue thread
CONCRETE OBJECTIONS · WHAT CRITICS POINT TO
• Not conservative — ProductionReady ships an opt-in relax of the 83-byte
• High drama — the launch was concurrent with the Knots / BIP-110 dispute and explicitly positioned against Core's direction. Critics read this as picking the loudest moment to ship a contested fork.
• No engagement — Song's post-launch X replies have been characterised by his critics as ignoring substantive technical questions, particularly on funding sources and decision authority within the 501(c)(3).
OP_RETURN default that Bitcoin Core 30.0 changed. Reverting an in-Core decision is, structurally, the opposite of "small change, low risk."• High drama — the launch was concurrent with the Knots / BIP-110 dispute and explicitly positioned against Core's direction. Critics read this as picking the loudest moment to ship a contested fork.
• No engagement — Song's post-launch X replies have been characterised by his critics as ignoring substantive technical questions, particularly on funding sources and decision authority within the 501(c)(3).
"3+ IMPLEMENTATIONS"
Song's structural claim is that 3+ independent implementations "create entirely different social dynamics". The 2025–26 wave is clustering by policy stance (loosen vs tighten data carriage) rather than by technical goals. Several efforts are still pre-mainnet. The bitprojects Sybil-node episode tied implementation choice to network-layer signaling games. Whether this validates or refutes the claim depends on what counts as a "different social dynamic."
Hornet — Consensus as a Spec
A clean-slate Bitcoin client by Toby Sharp; public artefacts are a paper and update posts, no source code released
WHAT IT IS
Hornet is a from-scratch Bitcoin node in modern C++ by Toby Sharp (mathematician; ex-Microsoft Principal Software Scientist, now at Google). The ambition isn't another client — it's an executable specification of Bitcoin's consensus rules. Site:
hornetnode.org.THE GAP
Bitcoin's consensus rules currently only exist inside Bitcoin Core, tangled with storage, networking, signature caching, and 15+ years of workarounds. Hornet aims to extract them into a standalone, auditable spec.
ARTEFACTS — PAPER ONLY
Public artefacts as of May 2026 are the arxiv paper (
2509.15754, Sep 2025) plus Delving / Optech updates on the architecture, consensus engine, and Hornet DSL. No source repo released. Sharp: "I'll make the code available when it's ready. Until then, there is nothing to check."