The problem I wanted to solve: Stockfish tells you what the best move is, but never why . Players under 1800 don't lose because they can't read centipawns — they lose because they don't understand plans, structures, key squares. What the tool does: Imports your games from Chess.com or Lichess Stockfish 17.1 WASM runs in your browser (fully local, nothing uploaded) A pattern detector finds 18 types of recurring mistakes across all your games (missed forks, exposed king, bad bishop, neglected development...) An LLM generates coaching narratives in the style of a 2700+ coach Instead of: -89 cp · Best: Nc3 Nf6 Be3 The AI coach says: "Bd3 is premature — the bishop attacks nothing and blocks d3 where the queen may want to go. Nc3 was the right move: it defends d4, prevents Black's ...e5 counterplay, and leaves the bishop free to settle on Be3 or Be2 depending on Black's plan." You can also chat with the coach — it knows your full game history, opening stats, specific weaknesses.…