Kaisersolver: A CoW Protocol Solver That Shows Its Work

To compete as a solver on CoW Protocol, you need a company behind you: incorporation papers, passports for the people running it, and a bond or someone willing to vouch for you. A developer with an engine that finds good prices, and nothing else, cannot take part.

So we became the company. Kaisersolver is the result: a CoW Protocol solver built by William and operated by Fiftysix. It went live on Arbitrum in May 2026, on Base in June, and on BNB Chain in September.

What a CoW Protocol solver does

When you trade on CoW Swap, your order does not go straight to an exchange. It joins a batch with other people's orders, and the protocol holds an auction for that batch. Solvers compete to find the best prices. The one that delivers the most to traders wins, settles the batch on chain, and is paid in COW.

It is a competition about who can make a trade better for the person making it. It only makes sense someone would be paid for that.

Kaisersolver is one of the solvers in that competition. It looks at each batch, searches public exchanges and market maker quotes for the best route, and bids. If it wins, the protocol checks the solution, signs it, and puts it on chain.

Why Kaisersolver exists

The protocol asks every solver for the same things, and they make sense. Someone has to be accountable when a trade goes wrong, and it cannot be an anonymous server.

But those requirements filter on paperwork, not on whether the code finds good prices. A developer can build an engine that competes with anyone and still be shut out because there is no company to put behind it.

Kaisersolver is our answer to that. An independent developer's engine, with a company standing behind it, competing on the same terms as everyone else.

Who builds it and who operates it

William built the engine and runs it. He goes by kaisersnipes on GitHub and the CoW forum.

Fiftysix is the entity of record. We passed KYC, we were vouched into the CoW DAO bonding pool, we receive the rewards, and we answer for it when something goes wrong.

That last part is not theoretical. Twelve days after launch, a settlement failed and the penalty came off our ledger, not William's. That is what standing behind something means. We wrote about the arrangement itself in how to become a CoW Protocol solver.

A solver that shows its work

Most of this industry asks you to trust it. We would rather you checked.

Everything Kaisersolver does is on chain, and at kaisersolver.com you can verify its newest settlement yourself, in your browser, with nothing to install. The tool behind that check, cow-certify, is free and open source, and it works on anyone's settlements, not just ours. It only calls something a violation when public data proves it. When it is unsure, it says so.

What Kaisersolver does not do

Kaisersolver never holds anyone's funds. Every trade settles in a single step through the protocol's own contract, so there is no moment where money sits with us. It holds no inventory of its own and is never the other side of a trade. It finds routes. It does not take positions.

What we have given back

A small solver notices things a large one has no reason to look at. We track everything we learn and use it to expand the solver space, and the infrastructure behind it, for the teams that come next.

Our measurements helped reshape a protocol rule on penalties. The tools we use to compete are open source. And we wrote the Solver Readiness Standard, a way for any new team to find out whether their solver is ready before it goes live. It is the check we wanted for ourselves.

Read more

The details each have their own article:

• How to become a CoW Protocol solver: what the protocol asks for, and what an operator of record carries.
• What it costs to run a CoW Protocol solver: what it takes to take part, and what it takes to win.
• cow-backtester: testing a solver against real auctions before it goes live.
• Who holds the keys to a solver's settlements: what the protocol controls, and what we do.

What comes next

Kaisersolver is early. It wins some auctions and sits out too many others, and we know which ones and why. The work now is closing those gaps, one route at a time, and bringing more liquidity within reach of CoW traders.

If you run liquidity that should be reaching CoW traders, or you are building a solver of your own and want to know whether it is ready, get in touch.

There is a lot of room at the top. We would rather get there with people than ahead of them.