CoW Protocol
CoW Protocol batches multiple orders together and finds Coincidence of Wants — matching traders directly to eliminate LP fees and MEV. Solvers compete to find the best settlement.
Batch Auction Visualization
Watch orders accumulate into a batch and get matched. Green lines show direct CoW matches; amber lines show AMM-routed fills.
Batch Size
8 orders
CoW Matches
3 pairs
Total Volume
$200K
Fee Savings
$180
Solver Competition
Multiple solvers compete to settle each batch. The solver returning the most surplus to traders wins.
Active Solvers
5
Winning Surplus
$342
Settlement Gas
$18
Net User Benefit
$324
How Coincidence of Wants Works
Without CoW (Traditional)
Alice wants to sell 10 ETH for USDC
Bob wants to buy 10 ETH with USDC
Both go through an AMM pool:
• Alice pays 0.3% LP fee = $9
• Bob pays 0.3% LP fee = $9
• Both suffer price impact
• Both exposed to sandwich attacks
Total cost: ~$30+
Bob wants to buy 10 ETH with USDC
Both go through an AMM pool:
• Alice pays 0.3% LP fee = $9
• Bob pays 0.3% LP fee = $9
• Both suffer price impact
• Both exposed to sandwich attacks
Total cost: ~$30+
With CoW (Batch Auction)
Alice wants to sell 10 ETH for USDC
Bob wants to buy 10 ETH with USDC
Solver matches them directly:
• Both trade at fair market price
• Zero LP fees
• Zero price impact
• Impossible to sandwich (off-chain)
Total cost: ~$0 (just protocol fee)
Bob wants to buy 10 ETH with USDC
Solver matches them directly:
• Both trade at fair market price
• Zero LP fees
• Zero price impact
• Impossible to sandwich (off-chain)
Total cost: ~$0 (just protocol fee)
Batch Auction Timeline
Each batch follows a precise timeline from order collection to on-chain settlement.
T+0s — Order Collection Opens
Users submit signed orders specifying sell token, buy token, limit price, and valid-to timestamp. Orders are collected off-chain in the order book.
T+30s — Batch Closes
The batch window closes and all collected orders are sent to registered solvers. Each solver has the same set of orders to work with.
T+30–45s — Solver Competition
Solvers compute optimal settlements: finding CoW matches, routing remaining volume through DEXs, and submitting their proposed solution with total surplus.
T+45s — Winner Selected
The protocol's driver ranks solutions by total surplus delivered to traders. The winning solver's solution is selected for on-chain execution.
T+45–60s — On-Chain Settlement
The winning solution is executed atomically on-chain via the CoW Protocol settlement contract. All matched orders are filled in a single transaction.
Surplus vs fee: CoW Protocol charges a small protocol fee, but the surplus from CoW matching and solver competition typically far exceeds this cost. In Q4 2024, CoW Protocol processed over $4B in monthly volume with an average surplus of 15bps per trade.