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Chess opening trainer

Know your openings. Remember them when it counts.

Import your repertoire, practice it with spaced repetition, and link your Chess.com or Lichess account. Out of Book checks every game against your preparation and shows you the moves you forgot and the replies you never prepared.

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Works with Chess.com, Lichess and over-the-board games.

Sample reportExample data: 212 games with the London System

212 games

London System (White)

  • Forgot a move30
  • Unprepared reply22
  • Stayed in book131
  • Other openings29

Moves you forgot

2

You were in your repertoire and played something else. These positions come back in practice.

  • 15 games · London System (White)

    1. d4 d5 2. Bf4 c5 3. e3 Qb6 4. Nc3

    You played 4. Qc1 (12), 4. b3 (3)

    PracticeOpen

    Last seen 2 Nov

  • 9 games · London System (White)

    1. d4 d5 2. Bf4 Nf6 3. e3 c5 4. c3 Nc6 5. Nd2 e6 6. Ngf3 Bd6 7. Bg3

    You played 7. Bxd6

    PracticeOpen

    Last seen 28 Oct

Replies you haven't prepared

2

Your opponent left your repertoire. Open the position to find a reply with the engine, then add it.

  • 11 games · London System (White)

    1. d4 d5 2. Bf4 Nf6 3. e3 c5 4. c3 Qb6

    Prepare

    Last seen 4 Nov

  • 7 games · London System (White)

    1. d4 d5 2. Bf4 Nc6 3. e3 Bf5

    Prepare

    Last seen 24 Oct

How it works

Three steps, and the third one keeps feeding the second.

  1. Line

    White to move

    1. 1.d4
    2. d5
    3. 2.Bf4
    4. Nf6
    5. 3.e3
    6. c5
    7. 4.c3
    8. Nc6

    Your move

    In repertoire

    Nd2

    Bring your repertoire

    Import a PGN from a Lichess study, ChessBase or any other file, or build lines move by move on the board with Stockfish beside you. Transpositions merge, so each position is studied once.

  2. 4. Nc3 is right.

    Practice with spaced repetition

    Play whole lines from the first moves. Each of your moves comes back right before you'd forget it, and the ones you miss come back sooner.

    • Blitz · 2 NovForgot 4. Nc3
    • Rapid · 31 OctNew reply 4... Qb6
    • Blitz · 29 OctIn book to move 9

    Check your games

    Link your Chess.com or Lichess account, or import over-the-board games with your FIDE ID. Each game is compared with your repertoire, and the moves you forgot go straight into practice.

Made for studying openings

  • Stockfish on the board

    The engine runs in your browser, only when you turn it on.

  • Weak spots

    Practice the positions your games actually reach, weighted by what your opponents play.

  • Notes on positions

    Write down plans and ideas, and see them while you practice.

  • Export any time

    Download your repertoire as PGN for Lichess or ChessBase, or all your data in one file.

Questions

Is it free?

Yes, completely. Every feature is free: repertoires, practice, the engine and the reports from your games. If you enjoy it, you can support it on Patreon (opens in a new tab).

Do I need to share my Chess.com password?

No. Chess.com games are public: you add your username and confirm it's yours with a short code in your Chess.com profile. Lichess accounts link through Lichess's own sign-in page.

Where do I get a repertoire file?

Any PGN works: export a Lichess study, a ChessBase database or your own notes. You can also start empty and add lines on the board.

Does it work with over-the-board games?

Yes. Add your FIDE ID and import the PGN files of your tournament games.

Can I use it on my phone?

Yes. It's a website, so it works on phones, tablets and computers, with nothing to install.

Start with the repertoire you already have.

Import a PGN or build your first line, then link your games when you're ready.

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