Random puzzles are useful, but sometimes you want practice connected to your own games. DeepBlunder looks for missed opportunities and turns those positions into a starting point for your next paper session.
Make a personal practice sheetChoose “Learn from my games.” Enter a Lichess username to request the latest ten completed standard games. The app identifies your colour from each game’s headers. Alternatively, upload a PGN file from Lichess, Chess.com or your chess software. For a manual export, select the colour you played in those games.
A local Stockfish engine evaluates your moves and screens for losses of at least 1.5 pawns compared with its preferred move. It then rechecks up to 24 candidates with a larger search budget. Analysis stays on your device. Uploaded PGNs stay in browser memory; successful public imports are cached in this tab and reused for five minutes, including across refreshes. This bounded search can overlook mistakes or change its verdict with deeper analysis.
Rule-based classifiers inspect engine lines and board geometry for forks, captures onto undefended squares and checkmate. Each suggestion has a supporting game position and explanation. If a specific pattern cannot be established, the app labels a broader opening, middlegame or endgame fallback rather than inventing a diagnosis.
“Recommended rated puzzles” selects related database exercises in your chosen difficulty band, weighted by the themes found. “Retry my own positions” prints the actual earlier positions from your games. These personal exercises are unrated and may have multiple reasonable moves; they are review prompts, not certified tactical puzzles.
Rated puzzles have QR codes to the interactive Lichess puzzle; your personal positions open an analysis board. Solve first on paper; scan when ready. See how printable QR worksheets work.