Where the puzzles come from
Real positions from rated online games
Every puzzle on this site is a position that came up in a real rated online game, with the winning line that was played or found in it. The puzzle data is public domain (CC0). We use the positions, ratings, themes and moves only: no images, software or branding from anywhere else.
- Collection date
- July 28, 2026
- Puzzles
- 49500
- Licence
- CC0 — no rights reserved
How each puzzle is checked
Before a puzzle is published, its position and every move of its solution are replayed with a chess rules engine, which also writes the move notation. A solution with an illegal move cannot pass this step, so a printed answer key always matches the board.