Ten chess engines, in your browser
No downloads, no configuration — they run on your own machine
Chess engines are normally native programs: you download a binary, find a graphical interface, and configure a UCI connection before you can watch one play. Every engine below runs inside an ordinary web page instead, compiled to WebAssembly — or in one case written directly in JavaScript. Because they execute on your own hardware rather than on a server, you can put any two of them against each other and watch live, for as long as you like, at no cost to anyone.
Stockfish 18
The strongest open-source chess engine in the world
Stockfish 17.1
The previous generation, still overwhelmingly strong
Stockfish 11
The last great engine before neural networks
Stockfish 10
A 2018 world champion, eight years out of date
Leela Chess Zero
A neural network that learned chess by playing itself
Reckless
A modern engine built from scratch, and genuinely strong
Koivisto
A strong independent engine with its own neural network
Rodent IV
The engine you can give a personality to
Texel
The engine that can genuinely play badly
Lozza
A chess engine written entirely in JavaScript
Put any two against each other
The Engine Arena runs any pairing live, optionally from a fixed opening chosen out of more than three thousand. The most instructive matchup is probably Stockfish 10 against Stockfish 18 — the same program eight years apart, disagreeing with itself.