Chessstack

Master Your Chess Openings

Build your opening repertoire, drill it with spaced repetition, and never forget your preparation again.

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Opening study shouldn't feel like guesswork

  • You study a line, then forget it a week later
  • You don't know which lines to study next
  • You can't tell where your repertoire has holes
  • You have no idea if you're actually following your prep in games
Chessstack repertoire builder showing chessboard with Stockfish analysis and masters database
Build

Pick the right moves with real data behind every choice

Build your opening repertoire move by move with five sources of move suggestions: a 21-million-game masters database, Stockfish engine evaluation, popular moves by rating bracket so you see what opponents actually play at your level, and a curated celebrity database featuring games from chess legends like Bobby Fischer, super GMs like Magnus Carlsen, and content creators like Daniel Naroditsky and GothamChess. Or import your existing repertoire from PGN files. No pre-made courses. Your repertoire, your choices.

Drill

Never forget a line with spaced repetition

The FSRS spaced repetition algorithm schedules your reviews at scientifically optimal intervals. Lines you struggle with come back sooner. Lines you know well fade into the background. No wasted repetition, no forgotten variations.

Chessstack spaced repetition drill session with confidence rating buttons
Chessstack opening trainer playing against a computer weighted by real game statistics
Train

Test your prep against an opponent that plays like a real human

Play against a computer that mirrors how real people play your openings. Each move is weighted by how often it appears in the Lichess masters database or at any rating bracket. If a move shows up in 40% of games, the computer plays it 40% of the time. Choose any starting position, set a depth limit, and play through your lines as many times as you want. Rated sessions track your Elo so you can measure real progress. When a session ends, review the game to spot gaps and build on your repertoire.

Puzzles

Stay sharp in the positions you actually play

Solve tactical puzzles filtered to your opening repertoire. Practice the combinations and patterns that show up in your games, not random positions you'll never see. Every puzzle links to the real game it came from so you can see the full context.

Chessstack puzzle training filtered by opening repertoire
Chessstack game review showing where player deviated from their repertoire
Review

Find out where you or your opponent left your preparation

Import your games from Lichess or Chess.com. Chessstack highlights every move where you or your opponent deviated from your repertoire, so you know exactly what to study next instead of guessing.

Prep

Know what any opponent plays and prepare against it

Enter any player's Chess.com or Lichess username and download their game history. Chessstack compares your repertoire to the lines they actually play, so you can build targeted lines or even a full repertoire against them and practice it in drill mode.

Chessstack opponent prep showing repertoire comparison against a specific player

Open-source. Self-host for free, or use the cloud.

Chessstack is fully open-source. Self-host it on your own machine with a single Docker command and get every feature with no limits, no subscriptions, and no data leaving your network. Prefer not to manage infrastructure? Use chessstack.app with one free repertoire, or upgrade for full access at a fraction of what other opening trainers charge.

Get Started Self-Hosting Guide

Frequently Asked Questions

What is a chess opening repertoire?

A chess opening repertoire is a set of pre-planned responses for the opening phase of a chess game. A complete repertoire covers both colors and includes responses to all common opponent moves, so you always know what to play in the first 10-15 moves of a game.

Why should I learn chess openings?

Studying openings helps you steer games toward positions you understand, save time on the clock in the early moves, and avoid falling into traps or lost positions before the middlegame even starts.

What is spaced repetition, and how does it help with chess?

Spaced repetition is a memory technique that schedules reviews at increasing intervals. When you get a move right, you see it less often. When you get it wrong, it comes back sooner. Applied to chess openings, it lets you memorize hundreds of lines without wasting time on the ones you already know.

How many opening lines do I need to know?

It depends on your level, but a focused repertoire of key lines beats memorizing everything. Start with responses to your opponent's most common moves and build depth over time. Quality matters more than quantity.

Should I study openings as a beginner?

A common misconception is that beginners shouldn't study openings. The hardest part of chess to learn is the middlegame, and it's hard to learn the middlegame if you keep entering it in a lost position. Even a simple repertoire helps you reach playable positions so you can focus on improving the rest of your game.

Can I use my own openings, or do I have to follow a course?

Chessstack lets you build your own repertoire move-by-move, and you can also import PGN files from other sources. The build tools (masters database, engine analysis, rating bracket stats, celebrity games) make it easy to find and add the right moves yourself.

How do I know if my opening preparation is working?

Import your games from Lichess or Chess.com and see exactly where you or your opponent deviated from your repertoire. Track your mastery percentage and gap coverage over time to measure your progress.