Alternative implementations
Other software that speaks Bitcoin — useful, risky, and deliberately rare.
In plain words
Bitcoin's rules live in running code, not on paper. A few programs besides Bitcoin Core speak Bitcoin — btcd, Libbitcoin, others. They serve research and keep Core honest. The danger is real: if two programs ever judge one block differently, the network splits in two. It happened by accident in 2013. So the discipline is strict — match Core exactly, bugs and all — and most nodes simply run Core.
Why it matters
- Consensus is the one place where "mostly compatible" means broken.
- Independent code guards against one catastrophic bug — that is the case for them.
- The 2013 accidental split set the culture: caution first.
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Updated 2026-07-29