Italian Game
Move 3 · you are White
| You | Bc4 | Still in the book |
|---|---|---|
| Opponent | h6 | Left the book |
| Book move | Bc5 | Giuoco Piano |
Free Chrome extension · chess.com and lichess
Learn chess openings while you play.
ChessDummy is a free Chrome extension for chess.com and lichess. It names the opening you are in, tells you the move where you or your opponent left the book, and lets you practice the right line as soon as the game ends.
Free. No account. Coming soon to the Chrome Web Store.
- 1,600 book positions
- 0 accounts needed
- 15 openings covered
From the game you just played to the line you will remember
Most opening tools ask you to study first and play later. ChessDummy starts from your own games, because the opening you just got wrong is the one you are most ready to learn.
-
1
Play as you always do
Open a game on chess.com or lichess. A small board sits in a corner of the page and names the opening as it develops: Italian Game, Sicilian Defense, Queen's Gambit.
-
2
See who left the book, and when
The moment a move leaves known theory, ChessDummy marks it and keeps the move number. You can blur the corner or hide it completely while the clock is running.
-
3
Practice the line straight after
When the game ends, choose “Practice this opening” to drill the book continuation on a separate practice page, or keep it for later. Lines you have learned are marked as known.
Built for club players, not for grandmasters
ChessDummy is for players rated roughly 800 to 1800 who want to stop losing the same opening positions, without signing up for a course.
-
Instant, and on your computer
The opening book ships inside the extension. Looking up a position never waits on a server, so the corner board keeps up with bullet, and your games are not sent anywhere.
-
No account and no sign-up
Install it and play. Your practice list and settings are stored in your own browser. There is nothing to log in to.
-
The mistakes you keep making
Add your chess.com or lichess username and ChessDummy reads your recent public games to find the opening positions where you go wrong again and again, then warns you when one comes up.
-
A book sized for real games
About 1,600 positions, chosen from how often club players actually reach them in rated Lichess games. No 30-move grandmaster theory you will never see on the board.
-
You choose how loud it is
Show the board, blur it until you look, or hide it during the game. One settings page, plain words, and it remembers your choice.
-
It never touches your board
ChessDummy reads the move list from the page. It never moves a piece, never submits a move, and never draws on the chess.com or lichess board.
The openings in the free book
Every line up to move 10 that club players meet regularly in these openings, with names from the open Lichess opening list. Other first moves are named, so you always know what you are looking at.
- Italian Game
- Two Knights and Fried Liver
- Ruy Lopez
- Scotch Game
- Four Knights Game
- Vienna Game
- King's Gambit
- Petrov's Defense
- Philidor Defense
- Sicilian Defense
- French Defense
- Caro-Kann Defense
- Queen's Gambit
- Slav Defense
- English Opening
ChessDummy is free. Later we plan to add a small paid set of extra openings that go beyond this regular list. Everything in the list above stays free.
How ChessDummy compares
Course platforms and repertoire builders are good at what they do. ChessDummy does a different job: it works inside the games you already play.
| ChessDummy | Course platforms such as Chessable | Repertoire builders such as Chessbook | |
|---|---|---|---|
| Where you learn | In the chess.com or lichess tab you are already playing in | On a separate site or app | On a separate site or app |
| What you study | The opening from the game you just played | A course written by an author | A repertoire you build move by move |
| Set-up before the first lesson | Install the extension | Create an account and pick a course | Create an account and build or import lines |
| Cost | Free | Free tier, paid courses and a subscription | Free tier with a move limit, paid plan |
| Best for | Players who want to fix openings without extra homework | Players who want deep, authored theory | Players who want to own a full repertoire |
Read the full comparisons: ChessDummy vs Chessable, ChessDummy vs Chessbook, and the best chess opening trainers compared.
Install ChessDummy in Chrome
It takes about a minute, and you do not need an account.
- 1
Add the extension
Add ChessDummy to Chrome on your desktop or laptop.
- 2
Open a game
Go to chess.com or lichess.org and start a game, or open the analysis board.
- 3
Pick how loud it is
On first run, choose whether the corner shows, blurs or hides during a game. Then play.
Questions people ask
Is ChessDummy free?
Yes. ChessDummy is free to install and use, with no account and no trial period. Later we plan to add a small paid set of extra openings beyond the regular list. The regular opening book stays free.
Which sites and browsers does it support?
ChessDummy works on chess.com and lichess.org in Google Chrome on Windows, macOS, Linux and ChromeOS. Other Chromium browsers that can install Chrome extensions, such as Edge and Brave, usually work too. It does not run in mobile browsers or in the chess.com and lichess mobile apps.
Is it allowed to use ChessDummy during a rated game?
Both chess.com and lichess allow opening books only in daily or correspondence games, not in live games. For live rated games, set ChessDummy to “Hide during the game” and switch off “Show the better move once someone leaves the book”. You still get the full review and practice the moment the game ends. Our fair play guide explains the rules on each site.
How is ChessDummy different from Chessable?
Chessable is a library of opening courses that you study on its own site with spaced repetition. ChessDummy is a browser extension that works inside your games on chess.com and lichess: it shows where you left the book and drills that exact line afterwards. Many players use a course for depth and ChessDummy to make the lines stick in real games. See ChessDummy vs Chessable.
What does ChessDummy do with my data?
Nothing leaves your browser. ChessDummy has no server and no analytics. Your settings and practice list are stored locally by Chrome. If you enter a username, the extension downloads your recent public games directly from chess.com or lichess to your browser. Read the privacy page for the details.
Which openings does it know?
The free book covers the lines club players meet most in 1.e4 e5 (Italian, Ruy Lopez, Scotch, Four Knights, Vienna, King's Gambit, Petrov, Philidor), the Sicilian, French and Caro-Kann, the Queen's Gambit and Slav, and the English, up to move 10. That is about 1,600 positions. Other openings are named for the first moves.
From the blog
Honest comparisons of opening trainers, and plain guides to learning openings.
-
Comparison
ChessDummy vs Chessable: which one helps you learn openings?
Chessable teaches openings through authored courses and spaced repetition. ChessDummy teaches them inside your own chess.com and lichess games. Here is how they differ and who each one suits.
Read the post -
Roundup
The best chess opening trainers in 2026, compared
Chessable, Chessbook, Lichess studies, Chess.com, Listudy, Chess Tempo and ChessDummy: what each opening trainer is good at, what it costs, and which one fits how you like to learn.
Read the post -
Comparison
ChessDummy vs Chessbook: build a repertoire, or learn from your games?
Chessbook helps you build and memorise your own opening repertoire. ChessDummy gives you opening feedback inside your chess.com and lichess games. A plain comparison of the two.
Read the post
More chess from Halfchess
ChessDummy is made by the team behind Halfchess. If you like chess that fits into a few spare minutes, try our other games.
Your next game is your next lesson
Add ChessDummy, play one game, and find out where you left the book.
Free. No account. Coming soon to the Chrome Web Store.