Tools for running your own Bitcoin infrastructure, with a focus on Bitcoin Blake2b (BitcoinB2B), the RDTS hardfork whose proof of work is BLAKE2b.
Self-hostable, built to run on hardware you control. No telemetry, no hosted service in the middle, no account required. The packaging here is GPLv3; each upstream keeps its own licence, and every repository states which.
More at twentyone.life.
It is a hardfork of Bitcoin. It shares Bitcoin's history up to the fork, genesis block included, and differs in how blocks are mined: the proof of work is BLAKE2b rather than SHA256d, and block headers are 164 bytes instead of 80. The change is described in bitcoinknots/bitcoin#359.
Because the proof of work differs, Bitcoin's software does not work on it. Bitcoin's Electrum servers cannot read this chain, which is why Shulcrum exists, and there are no public servers for it, so running your own is not optional here the way it is on Bitcoin. That is what the packages below are for.
It is a separate chain and a separate asset. Coins on it are not bitcoin. Addresses look identical because the format is shared, not because the two are interchangeable, which is worth remembering before sending anything anywhere, including to the address at the bottom of this page.
| Shulcrum | An Electrum server that indexes and serves chains with 164 byte block headers and BLAKE2b proof of work. A fork of Fulcrum by Calin Culianu, by way of Kilombino's BLAKE2b work. |
| shulcrum-startos | Shulcrum packaged as a StartOS .s9pk, so it installs on a StartOS server beside your node. |
| shrike-startos | Shrike, the Bitcoin Blake2b wallet by privkeyio, packaged for StartOS and served to your browser. Forked from remcoros's Sparrow package. |
| mempool-bip110 | A reference copy of the mempool explorer with BIP110 "Reduced Data" violation detection. Not modified here yet. |
As of 2026-09-23.
Shulcrum now negotiates protocol 1.8 on a chain with BLAKE2b headers, refuses to serve headers to clients that cannot read them, and reports the fork point so a wallet can tell this chain from Bitcoin. A regtest chain crossing its activation height exercises all of it, and a block hash that was wrong for post-fork blocks is fixed.
Mainnet verification is still in progress: an index of the live chain is roughly two thirds built by block count. Until it spans the fork height, the protocol work is tested rather than proven, and no wallet has been synced end to end.
The StartOS packages install and run on a real server. The wallet package serves a wallet to a browser; it has not yet served one that holds money.
Said plainly because "it compiles and syncs testnet" is not evidence about the chain people keep money on.
Releases are signed with:
09F6 80BB 428D 92E4 BEDC 8251 15DC 7438 A64C 9B6D
TwentyOne.Life <dev@twentyone.life>
The primary key certifies only and never signs a release; a subkey does that, so a compromised build machine costs a subkey rather than the identity. The address in that user id names the key, not a mailbox.
How to check a download, and what each failure means: verifying a release.
Donations in BitcoinB2B:
1BH665bXvEqSuoWQUihiQiPpt2BqpzrgGD
As a URI, which a wallet with a handler opens on a click, and which is what the QR encodes:
bitcoin:1BH665bXvEqSuoWQUihiQiPpt2BqpzrgGD
Read this before sending. Bitcoin Blake2b shares Bitcoin's address format and its genesis block, so the address above is a perfectly valid Bitcoin address as well, and nothing about it says which chain it belongs to. Send from a Bitcoin Blake2b wallet. Bitcoin sent to it is a different asset and is not a donation to this project, whatever your wallet shows you.
There is no way to make that distinction visible in the address itself. It is a property of the fork, not an oversight.