BitcoinBTC
The original chain. Every UTXO fork in this wiki shares its history up to a split block.
The baseline every fork measures itself against. The wiki treats Bitcoin as the root of the tree, not as the referee: each fork article states what it changed and lets the sources speak.[7]
Origins
Satoshi Nakamoto announced the Bitcoin white paper on the Cryptography mailing list on 31 October 2008[1]. The genesis block, block 0, is dated 3 January 2009[2].
The block size constant
Bitcoin's 1 MB block size limit was added in commit a30b56e on 15 July 2010[3]. When Jeff Garzik proposed a patch to raise it in October 2010, Satoshi replied "Don't use this patch" and said a change could be phased in later "if we get closer to needing it"[4]. That constant became the centre of the block size war[5].
Soft forks, not hard forks
Bitcoin's own rule changes have been soft forks: P2SH (BIP16) in 2012, CLTV (BIP65) in 2015, CSV in 2016, SegWit at block 481,824 in August 2017 and Taproot at block 709,632 in November 2021[6]. The chains that broke away, from Bitcoin Cash in 2017 to Bitcoin BLAKE2b and eCash (ECX) in 2026, are documented as separate articles[7].
How many forks?
forkdrop.io counts 105 projects that issued coins based on Bitcoin's ledger, 74 of them listed as active and 31 as historic[8]. Code forks that started from a new genesis block, such as Litecoin, Dogecoin, Dash and Zcash, are not in that count, but this wiki covers them as members of the wider family[9].
References
- primarySatoshi Nakamoto, “Bitcoin P2P e-cash paper”, Cryptography mailing list, 31 Oct 2008 [archived]
- primaryBlock 0 (genesis), mempool.space [archived]
- primaryBitcoin commit a30b56e, 15 Jul 2010 (adds MAX_BLOCK_SIZE = 1000000) [archived]
- primarySatoshi Nakamoto, reply to Garzik's block-size patch, Bitcointalk msg 15139, 3 Oct 2010 [archived]
- btkFork Wars: the block size war timeline (Bitcoin Takeover) [archived]
- btkBitcoin: All the Hard Forks and Soft Forks (BTCTKVR: Forks!) [archived]
- btkBTCTKVR: Forks! (2026 magazine) [archived]
- secondaryforkdrop.io, “How many Bitcoin forks are there?” (105 projects) [archived copy; original: https://forkdrop.io/how-many-bitcoin-forks-are-there, TLS certificate invalid on 2026-11-13]
- primarycoblee, “[ANN] Litecoin - a lite version of Bitcoin. Launched!”, Bitcointalk topic 47417 (opened 9 Oct 2011; launch noted as 13 Oct 2011 03:00 GMT) [archived]
- secondaryBitcoin Marketing Department, BLAKE2b fork media advisory (XBT naming) [archived]