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Architecture​

Three main sub-systems are required to facilitate and drive the auction

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Order book​

The orderbook is the main entry point of the protocol for traders. Using the orderbook’s API, UIs and other integrations allow traders to:
  • Get quotes for orders
  • Place orders
  • Cancel orders
  • Get the currently solved auction
  • Etc.
For instance, when you visit CoW Swap and place an order, the site uses the Order book API to add the order to a database. This database with all orders is shared with the autopilot.

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Autopilot​

The autopilot is a service that drives the core protocol functionalities with responsibilities including:
  • Creating and arbitrating auctions
  • Defining the timeline and valid orders for each auction
  • Orchestrating the revelation and settlement of the winning solver’s solution
  • Monitoring the competition
  • Serving as data consensus layer in the case of dispute or slashing by the DAO
  • Communicating auctions to all registered solvers

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Solvers​

For the sake of this documentation, we differentiate solvers into two sub-parts:

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Driver​

The Driver is the executive part of the solving process, and is responsible for:
  • Interacting with the blockchain in order to enrich, encode and eventually execute the settlement
  • Preparing all the data needed for the engine to match orders in the auction and forwarding the augmented auction to the engine
  • Receiving raw solutions from the solver engine, which it post-processes, simulates, merges, encodes into a blockchain transaction and finally scores
The driver interfaces with the autopilot and reports the best solution’s score to participate in the competition. If chosen as a winner of the auction, the driver is also responsible for getting the solution included in the blockchain.

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Solver Engine​

Solver Engines implement the pure matching logic, by employing different types of solving algorithms to optimally match traders with one another taking on-chain as well as private liquidity into account. They receive the pre-processed auction instance from the driver sub-component and return the solution together with instructions on how to achieve the fulfillment on-chain.
Last modified on March 4, 2026