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The Solver API defines the interface that solvers must implement to participate in CoW Protocol batch auctions. The driver communicates with solvers through this API.

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Endpoints

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Solve

  • POST /solve — Receive an auction instance and return proposed solutions
The driver sends the current auction (orders, tokens, liquidity sources) and the solver returns one or more settlement solutions ranked by objective value.

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Notify

  • POST /notify — Receive notification about auction results
After a batch is settled, the driver notifies participating solvers about which solution won and why.

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Integration

Solvers implement this API as an HTTP server. The driver connects to each registered solver’s endpoint during each auction cycle. For a complete guide on building a solver, see the Solver Tutorials. For the auction schema and competition rules, see Auctions.
Last modified on March 4, 2026