Powerful
Stockfish is no slouch—it plays on the same level as commercial engines like Rybka and Houdini. And it's the most powerful open source chess engine in the world. Source: CCRL
Open Source
Wondering how Stockfish works? You can take a look at the source code, available on GitHub. Plus, since Stockfish is released under the GPLv3 license, you can modify and redistribute the software. Restrictions apply.
Cross Platform
We provide binaries for every major desktop operating system, including for Windows, Mac OS X, and Linux. And you can always compile Stockfish from source for any platform you want.
Go Mobile
Want to do some chess analysis on the go? Get the Stockfish for iOS app, which runs on iPhone, iPod touch, and iPad. It has every feature you'd expect in a desktop-class chess program.