Definition
A feather fork is a censorship strategy that lets a miner with well under half the network's hashrate pressure others into excluding specific transactions. The attacker publicly announces that if it sees a block containing a blacklisted transaction, it will refuse to build on that block and instead attempt to fork around it, continuing for a limited number of confirmations before giving up.
The Coercion Mechanic
The threat works through expected-value math rather than brute force. An honest miner that includes the blacklisted transaction now faces a chance its block gets orphaned by the attacker's retaliatory fork, lowering its effective revenue. A profit-maximizing miner may therefore choose to drop the transaction to avoid that risk, even though the attacker lacks the hashrate to win outright. If enough miners reason this way, a sub-majority actor can enforce a partial blacklist at relatively low real cost.
Why It Is a Soft Attack
Unlike a hard fork, where a faction mines its own chain regardless of length, a feather fork keeps following the longest valid chain that excludes the targeted transaction and abandons the effort if it falls too far behind. This bounded, probabilistic nature is what makes it cheap to threaten but unreliable to execute. It contrasts with the absolute reordering power of a 51% attack.
Feather forking illustrates that censorship resistance is an economic property, not just a hashrate threshold. Related concepts include chain reorganization, selfish mining, and the broader role of proof of work in resisting coercion.
See who holds hashrate in the pool centralization tracker.
In Simple Terms
A feather fork is a censorship strategy that lets a miner with well under half the network’s hashrate pressure others into excluding specific transactions. The…