ChessStack

ChessStack is an open-source chess opening trainer built around the FSRS spaced repetition algorithm. It lets you construct your opening repertoire move by move on an interactive board, then quizzes you at scientifically timed intervals so the lines actually stick.

What makes ChessStack different from platforms like Chessable is the self-hosting option. You can run the entire application on your own server via Docker, with no subscription, no data leaving your network, and no limits. The included data pack ships with roughly 8.8 million master-level moves and over 2,000 Lichess opening-tagged puzzles, all loaded automatically on first startup.

The repertoire builder pulls suggestions from a database of 21 million games by players rated 2500 and above. Once your lines are in place, the drill mode schedules reviews using FSRS, the same algorithm behind modern flashcard apps like Anki. A gap finder automatically detects positions where you have no prepared response, so nothing falls through the cracks.

ChessStack also imports your games from Lichess and Chess.com, highlighting where you deviated from your prepared lines. The tactical puzzle mode filters puzzles to positions that actually appear in your repertoire, which means the training stays relevant to the openings you play. Built with Svelte and TypeScript, the project is actively maintained and licensed under AGPL-3.0.