Patzer

Chess.com locks unlimited post-game engine reviews and coaching explanations behind recurring subscriptions. Patzer runs that analysis, training, and coaching loop inside a single Docker container backed by Stockfish and your own Ollama or vLLM endpoint. Written in TypeScript on Hono and SQLite, it gives households and self-hosters a private chess server without subscription fees or cloud telemetry.

Where Patzer fits

Platforms such as Chess.com and Aimchess meter post-game review, move explanations, and mistake tracking behind monthly tiers that multiply across a household. Free servers like Lichess offer engine evaluation and opening explorers, yet they do not attach a local language model to narrate why a move fails or run as an isolated home appliance with kid guardrails. Patzer fills that gap by bundling Stockfish 17, SQLite, and a React chessground board into one container on port 8800.

From a cost perspective, operators eliminate chess subscriptions and cloud token bills by pointing Patzer at a LAN Ollama or vLLM host. The language model never evaluates positions on its own: Stockfish, chess.js, and a static exchange evaluator compute centipawn loss, hanging pieces, tactical threats, and player habits on the server first. The model only turns those verified facts into plain-language coaching, and a server check blocks any reply that contradicts the engine, letting small models like gemma3:1b or qwen2.5:7b coach at zero marginal cost.

What it does well

• Fact-grounded local AI coaching: Pairs Stockfish 17 and tactical detection with your Ollama or vLLM endpoint, linking blunders to patterns across your last ten games without hallucinating moves.
• Game Review and Elo estimation: Imports Chess.com and Lichess games or PGNs, classifying moves from Brilliant down to Blunder using win-percentage sigmoids and centipawn loss curves.
• Bot matches and live PvP: Lets players face seven Stockfish tiers with up to six premoves, or host live matches between local accounts with draw offers and rematches.
• Opening trainer and lessons: Ships 69 interactive lessons across four levels plus a spaced-repetition trainer for 16 built-in main lines and custom repertoires.