Chess AssistanceOpen source & free, for you~💖

40 000+

Installs

2000

Daily Uses

>80%

Positive Reviews

100+

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A.C.A.S (Advanced Chess Assistance System) is an open-source chess assistant (not a chess cheat), designed to help you make better moves using a chess engine. Just install the userscript, open the A.C.A.S GUI, and you're ready to go—no downloads necessary!

Completely free and open source! (Licensed with GPLv3 💖)
No anti-features on userscript (e.g. ads and tracking)
WebAssembly chess engine (faster than regular JavaScript engines)
Supports the most popular chess game sites (e.g. chess.com, lichess.org)
Supports multiple move suggestions, move arrow markings, chess variants & fonts
Translated to 30+ languages

▶️ Open A.C.A.S	⬇️ Install (GreasyFork)	⬇️ Download (Direct)	💬 Discuss With Community

Please be advised that the use of A.C.A.S may violate the rules and lead to disqualification or banning from tournaments and online platforms. The developers of A.C.A.S and related systems will NOT be held accountable for any consequences resulting from its use. We strongly advise to use A.C.A.S only in a controlled environment ethically.

Beyond Move Suggestions.

Our goal is to build chess software that benefits everyone. We aim to support new players by offering features that enhance learning and deepen understanding of the game.

A.C.A.S can render stuff right on the chessboard.

Settings for changing the engine and such. A.C.A.S offers great customization.

Customize it.

We’ve made it so you’re in charge, giving you full control over your experience. Whether you’re a newbie or a chess pro, it’s all about playing your way.

Okay, so what.

Tell you what. No subscriptions, no paywalls—just a ridiculously useful chess tool that works right on your favorite sites. That's what A.C.A.S is. Whether you're grinding puzzles, playing bullet, or trying to break 2000 Elo, A.C.A.S overlays insights directly on the board. It’s lightweight, it’s fast, and it doesn’t get in your way.

Just install it, keep the GUI open, and learn how to play better. Oh yeah and it works on literally all of your devices that has a modern browser, including your little phone, everything processed locally!

Ready to begin? Install now!

Are you a developer?

Please visit the development page.

A.C.A.S is currently in development. Expect bugs, especially on variants.

A.C.A.S V1 is no longer updated, but feel free to use it if it still works.