Stockfish
The world's strongest open-source chess engine. Free, free forever, and powering most of the other tools on this list under the hood.
No affiliate relationship with this tool. The link below goes directly to the product site.
Our take
Stockfish is the ground truth I cross-check everything else against. When a tool disagrees with Stockfish, I usually trust Stockfish. That said, it's an engine, not a teacher — pair it with something else if your goal is to understand positions rather than evaluate them. The depth-of-search rabbit hole is also real: don't let yourself chase +0.1 evaluations for ten minutes when you should be studying.
Stockfish is a free and open-source UCI chess engine developed by a distributed community of contributors. It currently sits at the top of every major engine rating list and serves as the analysis backend for Chess.com, Lichess, ChessBase, and most of the other products on this site. The current release is Stockfish 18 (January 2026), which brought a new neural network with threat inputs and a meaningful strength jump over Stockfish 17.
It’s a pure engine: you need a GUI or a tool that embeds it. Pretty much every analysis tool on this list uses it somewhere behind the scenes.
Pros
- Consistently the top-ranked engine in CCRL and TCEC rating lists
- Fully open source (GPL), actively developed — Stockfish 18 (January 2026) added roughly 46 Elo over its predecessor
- Runs on basically anything — your phone, your browser, a potato
Cons
- Raw engine only — no UI, no training features, no commentary
- To use it well you need a GUI like CuteChess, ChessBase, Arena, or a web wrapper
- Default settings can be overwhelming; most players don't need 60 depth
Related tools
ChessBase
The professional desktop software for database work, deep analysis, and tournament preparation. Now at ChessBase '26 with AI annotations.
Chessify
Cloud engine analysis in a browser. Run Stockfish at massive server speeds without installing anything.
Lichess Analysis Board
Free, open-source, ad-free analysis with Stockfish in the browser and a serverless cloud engine for deeper dives.