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What is BitcoinII?
BitcoinII (BC2) is Bitcoin’s design on a new network. Its whitepaper calls it “a faithful re-deployment of the original protocol”: the same monetary rules and SHA-256 proof of work, started from a clean genesis block with no premine.
BC2 addresses look identical to Bitcoin addresses. Always confirm the network before sending. BC2 is not BTC: don’t send BTC to a BC2 address, or BC2 to a BTC address.
Where it came from
- Dec 12, 2024: the genesis block (block 0) was created. Its hash is
0000000028f062b221c1a8a5cf0244b1627315f7aa5b775b931cfec46dc17ceb. - June 22, 2025: public mining began with block 1.
- Aug 18, 2025: the whitepaper was published.
- Aug 29, 2026: block 57,750 activated ShockWave, the data limits and replay protection (BitcoinII Core v31.1.0).
The whitepaper describes BitcoinII as “a second chance for those who missed Bitcoin’s earliest days”. That is about timing: the chance to run a node, mine and take part while a Bitcoin-style network is young.
The monetary rules
- Maximum supply
- 21,000,000 BC2
- Block time
- Targets 10-minute blocks; actual intervals vary with hashrate
- Block subsidy
- 50 BC2
- Halving
- Every 210,000 blocks; the first is at block 210,000
- Proof of work
- SHA-256 (SHA-256d)
- Software
- Based on Bitcoin Core v31.1; SegWit and Taproot supported
Technology
- SegWit and Taproot have been active since the network’s first few hundred blocks (SegWit from block 290, Taproot from block 300).
- Same consensus rules and tools as Bitcoin, with the BC2-specific changes listed below.
- No merged mining. SHA-256 hashrate goes to BitcoinII or to Bitcoin, not both at once. BitcoinII Core can run alongside Bitcoin Core on the same machine, with separate data directories and ports.
Issuance at a glance
| BitcoinII (BC2) | Bitcoin (BTC) | |
|---|---|---|
| Maximum supply | 21,000,000 | 21,000,000 |
| Launched | Dec 2024 (genesis) | Jan 2009 |
| Current block subsidy | 50 BC2 | 3.125 BTC |
| Next halving | Block 210,000 | — |
| Share of supply mined | TODO(verify): from live explorer data; not hardcoded | — |
A new chain, not a fork
A fork copies an existing blockchain and continues from there, so holders of the old coin also hold the new one. BitcoinII did not do that. In the whitepaper’s words it is “not a fork of the Bitcoin chain, not a sidechain, and not a derivative token.” It started from its own genesis block, nothing was copied from Bitcoin’s history, and holding BTC does not give you BC2.
Why difficulty started at 1
A new chain starting at Bitcoin’s current difficulty could not attract enough hashrate to be secure. Starting at difficulty 1, as Bitcoin did in 2009, lets security grow with the network’s real hashrate.
ShockWave difficulty adjustment
ShockWave is a per-block difficulty adjustment. It shipped in BitcoinII Core v31.1.0 and has been active since block 57,750, mined Aug 29, 2026 (UTC). It uses a 25-block rolling baseline derived from Dark Gravity Wave v3, allows at most a 4× change in difficulty per block, and includes an emergency recovery mode for when blocks stall. It targets about 10 minutes per block.
Why it was needed
Under the original 2,016-block retarget, hashrate tended to arrive in bursts and then leave, leaving the difficulty set for miners who were gone. From October 2025 to August 2026, blocks averaged about 51 minutes apart. The last epoch under the old rule averaged about 108 minutes, and the gap between two blocks exceeded 20 hours on 13 occasions, the longest being about 28.5 hours. Long, unpredictable gaps make confirmations slow for everyone: users, wallets and exchanges.
Since ShockWave activated, the longest gap between blocks has been about 4 hours. Block times still vary, as they do on any proof-of-work chain, but difficulty now responds within blocks rather than weeks.
ShockWave’s source is published on GitHub for review under its own proprietary source-review license; it is not covered by the MIT license that applies to most of BitcoinII Core. The whitepaper predates ShockWave, so its description of a 2,016-block retarget is historical.
Money, not data
The whitepaper rejects the expansion of OP_RETURN data limits adopted in Bitcoin Core v30, and commits BitcoinII to “Bitcoin’s original purpose as a borderless, censorship resistant, inflation proof, responsible monetary system”. Since block 57,750, consensus rules limit arbitrary data in transactions:
- At most one OP_RETURN output per transaction, up to 83 bytes.
- No Ordinals inscription envelopes, and no OP_13 Runes marker in OP_RETURN.
- No bare multisig outputs and no Taproot annex.
- Taproot script-path scripts are capped at 3,600 bytes.
These rules limit arbitrary data; they do not make it impossible to put any data on chain.
Other differences from Bitcoin
- Replay protection from block 57,750, so BC2 transactions can’t be replayed on another chain.
- Fork-aware header sync.
- Its own network: P2P port 8338, its own data folder and its own process.
A complement to Bitcoin
“BitcoinII does not ask users to abandon Bitcoin.” The whitepaper describes it as “not competition to Bitcoin, but complement: a second option, based on the same protocol”. Both can run on the same computer, with separate data folders, ports and processes. The project’s developers call it a sister chain.