These analysis engines are all very strong (ratings list here). If you know of any good programs I’ve missed, let me know.
- Stockfish (Free: Linux, Win, Mac, Android, iOS)
- Berserk (Free: Linux, Win, Mac[?])
- SlowChess Blitz (Free: Win, Linux)
- Houdini ($: Win)
- Komodo ($ for latest / Older versions are free: Linux, Win, Mac, Android)
- Shredder ($: Linux, Win, Mac)
- Fire (Free: Win)
- Critter (Free: Linux, Win, Mac, Android)