: Puzzles are grouped into 5 main folders (A through E) and subdivided into 495 specific PGN files by ECO code.
While the official Lichess database provides puzzles in a single large CSV or BZ2 file, the "By ECO" organization was a specific project shared by community members: download all puzzles - Lichess.org
: Each puzzle entry includes the starting FEN, the move sequence to solve it, the puzzle's rating, and "Themes" tags (e.g., fork, pin, mate in 2).
These zip files are typically PGN (Portable Game Notation) collections structured so you can practice tactics specifically related to certain openings:
