Blunderproof: Free Chess Review & Coach

Free game review for Chess.com and Lichess, with a coach that explains every move in plain words. Runs on your computer.

Blunderproof is a free chess coach that reviews your games, finds your patterns, builds you a plan, and gives you a drill for every step of it. REVIEW YOUR GAMES • Connect your Chess.com or Lichess username (no password needed) and pick a game. • Every move is graded: Brilliant, Best, Excellent, Good, Book, Inaccuracy, Mistake, Miss or Blunder. • The coach explains what each move does, what was better and why, what your opponent was threatening, and what happens next. It also names the other moves that were fine, and says what a trade does to the pawns. • Still confused? "I still don't get it" explains what's wrong with your move and why the better move is better, then plays it out on the board. • "Show best move" plays the engine's choice on the board and tells you why it's best. • Move the pieces yourself to explore your own what-if lines. • A "Review in Blunderproof" button appears on your finished games on Chess.com and Lichess, and the review starts the moment you open it. YOUR PLAN • My patterns reads your games and puts together a short plan: the exact things to work on, most useful first, each with the numbers behind it. • Every step has a Start button that opens the drill for it. • Results by colour, time control and opponent strength, your best and worst openings, how your games end, accuracy by game phase, and the wins that slipped away. • A weekly check-in: this week against last week. • Session guard: a small reminder after a game when your plan says it's time to stop (never during a game). TRAIN • Puzzles: 178,000 rated puzzles from the Lichess database, in 31 themes (hanging pieces, forks, pins, mates and more), matched to your puzzle rating. • Puzzle Rush: 3 minutes, 5 minutes or survival. How many can you solve? • Openings: learn the first moves of any opening, then play them from memory. Starts with the openings you actually play. • Winning positions: finish off positions you were winning in your own games, plus the basic mates and endings, against a strong bot. • Visualize: moves in your head, blind puzzles, and quick square drills, to train seeing ahead. • Puzzles from your own mistakes, which come back until you know them. PLAY BOTS THAT FEEL HUMAN • Bots from 400 to 2200, measured on real Chess.com and Lichess games, that choose moves and use their clock like real players. • Blunder check: stops you before a move that throws away material, so you can look again. • Every time control, pause, premoves, and looking back through the game while you play. FAIR PLAY Blunderproof never works during a game in progress. The review button and the session guard only appear after a game is over, and live games are refused. PRIVATE BY DESIGN No account, no tracking, no ads. The Stockfish chess engine runs on your own computer. The only thing Blunderproof sends anywhere is your username, to Chess.com or Lichess, to download your public games. Light and dark mode, 8 board colours and 7 piece sets. Menus and buttons in 51 languages (the coaching explanations are in English for now). Free. Chess engine: Stockfish (GPLv3). Puzzles and opening lines: Lichess (CC0). Blunderproof is an independent project and is not affiliated with Chess.com or Lichess.