Personal chess database

Blunderbase imports your games, runs Stockfish and Maia over every one of them, and keeps notes, stats and an opening explorer on top. Free, open source, runs on your own machine.

Download Try the demo View on GitHub

macOSWindowsDockeriOS companion

The game screen: the board with the engine's line drawn on it, Maia's move probabilities, Stockfish's lines, the move list with blunder badges, and the eval graph. — The game screen. Stockfish's lines drawn on the board, Maia's guesses beside them, the eval graph underneath.

What it does

Game analysis

Stockfish grades every move. Maia, trained on human games, says what players at several ratings would have played instead. Blunders are marked in the move list and on the eval graph, and the engine lines are drawn on the board.

Personal database

Your games from Lichess, Chess.com, FICS and PGN files in one library, synced on a schedule. Notes on positions and variations, an explorer with win stats over your own games, and reference games you add to study.

AI coach

An MCP server is built in. Connect Claude or any other MCP client, ask about last week's games, and it reads the same engine numbers and notes you do, on a live board you both see.

Server and Docker installs only. The desktop app has no MCP server yet.

Analysis needs an engine. The Docker image ships Stockfish. The desktop app uses a Stockfish on your machine, the browser's WebAssembly build, or a remote runner. Maia is a separate download in every case, and without it the human-move overlay stays empty.

On your phone

The iOS companion connects to a Blunderbase you host. Games list, game screen with the eval graph and the moves, notes, and live engine analysis that runs on the server rather than the phone, so the numbers match what the browser shows.

Not on the App Store yet. It is in TestFlight: open an issue on GitHub and ask for an invite. Android is on the roadmap.

Features

Import games from Lichess, Chess.com, FICS and PGN files
Analyse your games with multiple engines
Maia at multiple ELOs, to see what humans would have played
Notes on positions and variations
Engine lines drawn on the board, not just listed
Full MCP support: discuss games with an AI agent on a shared live board
Local engines, and Stockfish as WebAssembly in the browser
Remote engine runner: use your company's idle inference-server CPUs for your hobby
Game explorer with win stats over your own games, next to the Lichess database and its 8 billion games
Reference games added to your library for analysis and notes
Stats by opening, colour, time control and phase of the game
Fully self-hostable, easiest via Docker. One SQLite file, verified backups, PGN export

Around the library

The overview: rating over time per platform, recent games, the worst moments of the last thirty days, the analysis queue. — The overview: rating, recent games, and the worst moments of the last thirty days.

The explorer: a position on the board, the moves played from it with win rates over your own games, and the games that reached it. — The explorer. Your own move tree with win rates, next to the masters and Lichess books.

Stats: blunders by game phase, performance by time control, eval loss by clock remaining, and progress over time. — Stats. Blunders by phase, by time control, by how much clock was left.

The games list, filtered, with opening, result, rating change and blunder count per game. — The library, with filters that stack and the blunder count on every row.

Get it

Desktop

A single app for macOS and Windows with the backend inside. No terminal, no container, no account. Your library lives in the normal application-data folder. Point it at a Stockfish on your machine, or let the browser's WebAssembly build do the work.

macOS (Apple silicon) Windows (x64)

Unsigned builds for now: macOS asks you to allow the app in System Settings, Windows shows a SmartScreen notice. Intel Macs and Linux are on the roadmap.

Docker

# A sample compose file: one service, one volume.
curl -O https://blunderbase.org/docker-compose.yml
docker compose up -d
# Or without compose:
docker run -d --name blunderbase -p 8765:8765 \
  -v blunderbase-data:/data \
  ghcr.io/philphilphil/blunderbase:latest

Open it in a browser, choose a password, connect an account. That password is also the coach's key. TLS, reverse proxies, remote engine runners and the CLI are in the docs.

Roadmap

Desktop app for Linux
Companion app for Android
Sync service to keep several Blunderbases in step
Multi-engine analysis on the same game, for the engine nerds
Puzzles out of your own games
Import other people's games for study