Crypto glossary
ZK coprocessor
A ZK coprocessor runs heavy computations off-chain, often over historical blockchain data, and returns a zero-knowledge proof a smart contract can verify.
Smart contracts are limited in what they can compute and see: they cannot cheaply loop over thousands of past transactions or read an account's balance from a year ago. A ZK coprocessor fills that gap. A contract or user requests a computation, the coprocessor reads the needed data from block headers and state proofs, runs the computation off-chain and returns the result with a proof that ties it to the canonical chain.
Use cases include rewarding traders based on their historical volume, checking airdrop eligibility from past activity, computing long-term time-weighted average prices, verifying governance participation and running machine-learning or risk models whose output a DeFi protocol then trusts. Several teams offer coprocessors, often built on zkVMs.
Unlike an oracle, a coprocessor's answer can be verified cryptographically rather than trusted, but only to the extent that the circuits and proof system are correct. Proofs add latency, from seconds to minutes, and cost, so the approach suits computations that would be prohibitively expensive on-chain rather than simple queries.
Example
A DEX uses a ZK coprocessor to prove each trader's total volume over the past six months and pays fee rebates directly from a contract that verifies the proof, without trusting an off-chain database.