Caissa Codex

Chess openings explorer

3,690 named chess openings and variations, filed by ECO code from A00 to E99, each with its moves on an interactive board and win rates from millions of Lichess games. Free, with no ads.

Chess diagram: Scandinavian Defense: Modern Variation Opening of the day, November 11 Scandinavian Defense: Modern Variation B01 1. e4 d5 2. exd5 Nf6

The five ECO volumes

  1. A Flank Openings 791 lines
  2. B Semi-Open Games 758 lines
  3. C Open Games 1,238 lines
  4. D Closed & Semi-Closed Games 550 lines
  5. E Indian Defenses 353 lines

Famous openings

The lines you have probably heard of. Start here if you do not know where to look.

The 100 most-played openings

Famous gambits

Sharp, sacrificial openings where one side gives up material for initiative.

The 100 most-played gambits

Openings by first move

White's most played first moves, Black's main replies and White's main second moves, with the share of the games each one gets on Lichess.

1.e4 King's Pawn Game 59%

1.d4 Queen's Pawn Game 27%

1.c4 English Opening 3.9%

1.Nf3 Zukertort Opening 3.6%

Other first moves

A first move's percentage is its share of all games; a reply's or a second move's, its share of the games that reach the move above it. Rated Lichess games between players rated 1600 to 2500. Opening trends since 2016

Rankings from Lichess games

Which openings score best for each side, which are played most and which more than ten years ago, and the most-played gambits.

How the openings are organized

Every opening here carries one of the ECO codes, a system that files chess openings into five volumes: A, flank openings such as the English and the Réti, plus the Dutch and the Benoni; B, semi-open games such as the Sicilian, the Caro-Kann and the Pirc; C, open games after 1.e4 e5, plus the French Defense; D, closed and semi-closed games after 1.d4 d5, such as the Queen's Gambit, plus the Grünfeld; E, Indian defenses such as the Catalan, the Nimzo-Indian and the King's Indian.

Names and move orders come from the Lichess chess-openings dataset: 3,690 named lines spread over almost all of the 500 ECO codes. Each opening page shows the moves on an interactive board, where the line sits in the opening tree, its sub-variations, and how it scores in Lichess games between players rated 1600 to 2500, so you can see how an opening actually does, not just how it starts.

Know the moves but not the name? Search by moves or by FEN. Want to practice? Every line can be drilled from memory, or played out against Stockfish at six strengths, right in your browser.

https://chesscodex.org/