Fork Watcher
A specialized tool/service that tracks blockchain forks or abnormal reorganizations, alerting operators to possible chain splits.
A fork watcher is the dedicated tooling that does fork detection as a continuous service, alerting operators when something unusual happens at the chain-consensus layer.
A public example is forkmonitor.info, which as of October 2026 names Localhost Research as its sponsor. It does several things at once:
- Runs several Bitcoin node implementations side by side. As of October 2026 that means Bitcoin Core in versions from 0.8.6 up to a 32.0 release candidate, plus btcd and bcoin.
- Watches for chain divergence between any of them.
- Keeps a list of stale blocks: heights where two competing blocks appeared, with which node saw each one first and which one stayed in the main chain.
A watcher like this matters most when nodes disagree about the rules, because nodes that disagree end up on different chains. In August 2026, nodes running Bitcoin Knots releases that enforce BIP-110 rejected the main chain's blocks and split off onto a chain of their own. forkmonitor.info's list shows that split: at each height from 961,632 to 961,639 it has the main-chain block, mined on August 8, next to a competing block mined between August 8 and August 28.
Key takeaways
- Monitors for chain reorganizations or unexpected forks
- Runs several node versions or implementations side by side and compares the chains they follow
- Matters most when nodes disagree about the rules, as in the August 2026 split over BIP-110
Corrected
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Was: The entry said forkmonitor.info runs Bitcoin Knots and libbitcoin nodes alongside Bitcoin Core and btcd, and publishes alerts to RSS, Twitter and mailing-list feeds.
Now: As of October 2026 the site runs several versions of Bitcoin Core plus btcd and bcoin, compares the chains they follow, and keeps a list of stale blocks. It names Localhost Research as its sponsor. Details
Sources (3)
- Bitcoin Fork Monitor (forkmonitor.info) - nodes and footer on October 10, 2026: Bitcoin Core 0.8.6, 0.18.0, 31.1 and 32.0 rc2, btcd 0.26.2 and bcoin 2.2.0, each with its best block hash and height; the footer describes the site as monitoring multiple node implementations to detect consensus discrepancies and chain forks, and names Localhost Research as sponsor
- Bitcoin Fork Monitor - List Of Forks (competing blocks at the same height, which version saw each first, and which one stayed in the main chain; heights 961,632 to 961,639 each show a main-chain block from August 8, 2026 and a competing block mined between August 8 and August 28, 2026)
- bitcoin/bips PR #2245 - BIP 110 status changed to Closed (opened August 9, 2026); notes Knots released it on mainnet and on August 8 its nodes began rejecting non-signaling blocks, split to a new chain and stalled
Related terms (6)
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