The chain · XBT / BTCB2 explainedWhat XBT is

XBT, BTCB2, Bitcoin BLAKE2b, BIP-110

All four names mean this chain. Its coins are written XBT here and on the pools, and exchanges such as NonKYC list them as BTCB2. "Bitcoin BLAKE2b" comes from the proof of work. "The BIP-110 fork" comes from August 2026, when nodes enforcing BIP-110 stopped accepting blocks from the large SHA-256 miners that would not signal for it. The chain those miners kept is the SHA-256 fork; Bitcoin moved its proof of work to BLAKE2b three weeks later. The pool site covers BIP-110 and the split in more detail.

The fork

On 30 August 2026, at block 961,640, this chain stopped hashing with SHA-256 and started hashing with BLAKE2b-256. Blocks from that height carry a 164-byte header instead of Bitcoin's 80-byte one, which is why SHA-256 mining hardware cannot work here and why software has to be built for it.

Everything below that height is Bitcoin's: the same blocks, the same transactions, the same balances at the same addresses. Above it the two chains go their own way. Coins mined here are quoted as XBT to keep the two apart in writing and on exchanges.

What did not change: 21 million coins, the halving schedule, a 3.125 XBT subsidy at this height, ten-minute target spacing, retargeting every 2016 blocks, and the script rules your wallet already understands.

Addresses: the one real trap

This cuts both ways: if you held bitcoin before the split, the same balance exists here, at the same address, and only your key can move it. A key that has been used on the SHA-256 fork may be exposed to that fork's software too, so decide carefully before you move it.

How mining works here

Most of this network's hashrate runs DATUM: the miner's own node builds the block template, and the pool only issues the coinbase split and verifies shares. It puts transaction selection back with miners rather than with a handful of pool operators, which was much of the point of changing the proof of work in the first place.

Pools that still build every template themselves, and hold rewards in their own wallet, are the exception here rather than the rule. Lazarus keeps a public stratum as a donation, validation and fallback endpoint at 100%, with a grace at 25% then 100%, and charges 0% when the miner builds the block. The galaxy map reads every block's coinbase and shows which pools do which, straight from the chain.

How pools pay here

Because rewards are paid inside the coinbase of the block that earned them, a payout and a block are the same event: no pool holds a balance for you, and nothing is owed if a pool disappears overnight. Each pool sets its own split and window — the Lazarus Pool site documents the one it uses.

The long coinbase maturity soft fork

From block 973,440 to block 979,918, Bitcoin Knots 29.4.2 requires newly mined coins to wait 6,480 blocks (about 45 days) before they can be spent, instead of the usual 100. From block 979,919 (about 1 November 2026), Bitcoin Knots 29.4.3 raises that to 25,920 blocks (about 180 days), until the RDTS expiry in September 2027. Each coin's wait counts from its own block. It is temporary, and its purpose is to make hit-and-run mining — arriving for a difficulty dip, dumping the reward, leaving — unprofitable, while miners who stay are unaffected.

If you mine

Payouts arrive in the coinbase exactly as before and are yours on chain immediately; they simply cannot be spent until they are 6,480 blocks deep (mined before block 979,919) or 25,920 blocks deep (mined from block 979,919).

If you run a node

Upgrade to 29.4.3 before block 979,919. An older node accepts blocks the network rejects, follows dead chains, and if it builds your templates, everything it mines is wasted.

Coins from the first window

Consensus releases them at block 979,920, but Knots nodes do not relay a spend of any coinbase mined before block 979,919 until it is 6,480 blocks deep, so in practice each unlocks about 45 days after its own block, not all at once.

The longer maturity is now in force (Knots 29.4.3, #468). Withholding rewards for blocks produced by pool stratum rather than by a miner's own node has been discussed publicly by the Knots authors and is not in force. Read the original proposal.

Holding XBT

Two practical options today:

An Electrum wallet, pointed at a server for this chain

Fast, no sync, no disk. Use our public server at electrum.lazarus-xbt.xyz:50002:s (SSL, protocol 1.8) with a wallet made fresh for XBT.

Your own node

Bitcoin Knots 29.4.2 built for BLAKE2b, with its own wallet. Slower to set up, answerable to nobody. The node directory has builds and a reference config.

Glossary

BLAKE2b

The hash function this chain's proof of work uses instead of SHA-256. BLAKE2b vs SHA-256.

Coinbase

The first transaction in a block, which creates the reward. Pools here pay miners inside it, so a payout and a block are the same event.

DATUM

A protocol where the miner's node builds the block template and the pool only sets the payout split.

Gateway

The DATUM software a miner runs beside their node; their own miners connect to it. Either a C datum_gateway fork or ratum-gateway, a Rust rewrite that reads the same config. Which build to run, ranked by what we measured, is on the Connect page, with setup guides for FlyTheElephant and Ratum.

Prime

The pool-side server a gateway talks to; each pool runs its own.

TIDES

A payout scheme built on a rolling window of accepted work, paid in each block's coinbase.

Window share

Your fraction of the work in the current window — what the next block would pay you, which is not the same as your hashrate.

Maturity

How long a coinbase output must wait before it can be spent: normally 100 blocks; 6,480 for coins mined from block 973,440 to 979,918 and 25,920 (about 180 days) from block 979,919 under the soft forks.