Features:
- Chess opening tree with game statistics
- The Encyclopedia of Chess Openings (ECO)
- Database of top 100+ grandmasters’ repertoires
- Stockfish chess engine analysis
- Compare ECO, opening tree and engine moves side by side in any position
- Import and export chess openings in PGN format
- Build your own opening repertoire
- Add or edit comments on moves
- Automatically classify any sequence of moves using the ECO system
- Chess opening explorer highlights moves already in your repertoire
- Chess database includes all transpositions
- Interactive trainer to memorize your chess openings and variations
- Train multiple variations at once against random opponent moves from your repertoire
- Set up a starting position for training
- Track your training progress
- Customize chessboard colors and chess pieces
- Supports dark mode
- No ads
- Works completely offline

CHESS OPENING EXPLORER
Search in the Encyclopedia of Chess Openings, browse the chess opening tree, explore the opening repertoires of famous chess grandmasters, or ask the chess engine to find the best moves. Swipe left or right to switch between the exploration features in any position.

BUILD YOUR OPENING REPERTOIRE
Add your favorite opening lines to your repertoire using the chess opening explorer or import your openings in PGN format from other chess programs. You can always edit the names of your openings and organize them in your repertoire.

OPENING TRAINER
A simple and efficient method to memorize variations of openings in your repertoire. You can train either white’s moves or black’s moves only or both. Optionally, you can train all variations at once. The trainer chooses the opponent’s moves randomly from your opening repertoire. Chess Opener tracks your progress and shows your stats.