Stockfish

Strong open-source chess engine

Free, open-source, and cross-platform chess engine, trusted by grandmasters and leading chess platforms worldwide.

Download View on GitHub

Latest from the blog

2026-09-05: Stockfish 19
2026-01-31: Stockfish 18
2025-03-30: Stockfish 17.1

Trusted Worldwide

Powering analysis for leading platforms and millions of chess players.

Lichess

ICC

Chessis

What is Stockfish?

Stockfish is a chess engine. It analyzes chess positions, evaluates them, and tries to find the best move. It communicates with chess apps via the UCI protocol.

Player

Chess GUI


            position startpos
go depth 20

UCI Protocol

Eval: +0.30
Best Move: e4

Stockfish

One Engine. Unlimited Interfaces.

Stockfish evaluates the moves and you choose the chess app, GUI, or website you love most.

Web Platforms Desktop GUIs Mobile Apps

Chess.com

Lichess.org

En Croissant

Why Stockfish?

Built for peak performance, community collaboration, and universal accessibility.

Community-Driven

Developed by a global community of chess enthusiasts and programmers and released under the GPLv3 license, so everyone can read the code, modify it, and contribute back.

Join our Discord

Fishtest Framework

A massive distributed testing framework powered by community CPUs, validating every single code change across millions of test games.

Contribute ♥

Cross-Platform

Available on Windows, macOS, Linux, Android, and iOS. You can get world-class chess analysis wherever you are.

Download

Strong

One of the strongest chess engines in the world. Winner of the Top Chess Engine Championship and Chess.com Computer Chess Championship, and consistently ranks highly on rating lists.

View competition results

NNUE Evaluation

Efficiently Updatable Neural Networks (NNUE) provide fast and precise positional evaluation trained on billions of chess positions.

Learn about NNUE

Advanced Search

Highly optimized alpha-beta search with aggressive pruning and deep tactical tree exploration.

View Source Code