LucasChess

LucasChess is a free, open-source desktop chess training program built in Python and released under the GPL 3.0 license. It comes loaded with 125 built-in chess engines including Stockfish, Komodo, Houdini, Rybka, and Lc0, giving you access to one of the most comprehensive engine libraries of any free chess tool. It runs on Windows, Mac, and Linux, and a portable version is available so you can run it from a USB drive without installing anything.

One of the standout features is how LucasChess handles your mistakes. When you blunder, the program can automatically convert that position into a personalized training puzzle. Over time, this builds a custom puzzle set drawn directly from your own games, making your practice directly relevant to your actual weaknesses. This is a training loop that most paid platforms charge a premium for, and LucasChess gives it away for free.

The program supports a wide range of training modes: playing games against any of the 125 engines at adjustable strength, running engine analysis on your PGN files, working through openings with PolyGlot books, and running engine-versus-engine tournaments. There is also a strength determination feature that helps you calibrate your rating against the built-in opponents.

LucasChess is especially well-suited for players who want a serious offline training environment without a subscription. It has no internet requirement, no ads, and no paywalls. If you prefer working at a desktop with full control over your training, LucasChess is one of the best tools available in any price range.