ChessGrammar – API that detects tactical patterns in chess positions

Show HN: ChessGrammar – API that detects tactical patterns in chess positions

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I built an API that takes a FEN or PGN and returns every tactical pattern it finds — forks, pins, skewers, discovered attacks, back rank mates, and more (10 patterns total).It uses a two-phase approach: fast geometric detection, then sequence confirmation to filter out false positives.You can try it directly in the playground (no signup, no API key): https://chessgrammar.com/playgroundPaste any FEN or a full PGN and see what it finds. The playground also has a bug report button if something looks wrong.API docs: https://chessgrammar.com/docsBuilt with Python (python-chess), deployed on Vercel. The engine runs custom heuristic algorithms — no Stockfish dependency at runtime.Curious to hear fe

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Website: chessgrammar.com/playgroundPaste