A.C.A.S (Advanced Chess Assistance System)
[!WARNING]
A.C.A.S is currently in development. Expect bugs, especially on variants.
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!
[!CAUTION]
The use of A.C.A.S may violate the rules and lead to disqualification or banning from tournaments and online platforms. A.C.A.S is meant to be used as a real-time learning tool. Remember, struggling at chess doesn't mean you're unintelligent... it's not an IQ test, just a board game. And even IQ tests only measure certain aspects of your abilities. Use A.C.A.S fairly, be kind to other players.
| ▶️ Open A.C.A.S | ⬇️ Install (GreasyFork) | 💬 Discuss With Community |-------|-------|-------|
- Many built in WebAssembly engines (faster than JS)
- External engines (via an installable localhost server)
- Supports top chess sites (chess.com, lichess.org, etc.)
- Multiple suggestions, arrows, variants, fonts
- Multi-engine support, each with own settings
- Ability to modify any engine UCI options (e.g. ELO, depth, multiPV, skill)
- Visual board metrics (safe, contested, enemy squares, captured pieces)
- Move feedback and opponent predictions
- Render directly on external boards (or stay hidden via ghost mode)
- Audio TTS suggestions with adjustable speed
- Floating panel for stability and faster calculation
- Customizable themes (colors, fonts, textures)
- Chess variants supported (chess960, Fairy Stockfish variants)
- Translated into 30+ languages
- No anti-features on userscript
Used Libraries ❤️
| Library | Description | License | |--------|------------|---------| | Fairy Stockfish WASM | Chess engine (variants) | GPL-3.0 | | Stockfish WASM | Chess engine (main engine) | GPL-3.0 | | ZeroFish | WASM port of Lc0 + Stockfish | GPL-3.0 | | Maia-Chess | Human-like NN weights | GPL-3.0 | | Maia-Platform-Frontend | Maia 2 engine source | MIT | | Lozza | Additional chess engine | MIT | | COI-Serviceworker | Enables WASM on GitHub Pages | MIT | | ChessgroundX | Chessboard UI (modified) | GPL-3.0 | | FileSaver | Save config files | MIT | | bodymovin (lottie-web) | SVG animations | MIT | | chess.js | Game logic (Maia 2) | BSD-2-Clause | | onnxruntime-web | Run ML models in browser | MIT | | Klaro! | Cookie consent manager | BSD 3-Clause | | SnapDOM | DOM → image screenshots | MIT | | UniversalBoardDrawer | Draw arrows on boards | GPL-3.0 | | CommLink | Cross-window communication | GPL-3.0 | | Bootstrap Icons | Icon set | MIT | | Mona Sans | Font (GitHub) | SIL Open Font License | | Rubik | Sans-serif font | SIL Open Font License | | IBM Plex Sans | IBM typeface | SIL Open Font License | | ws | WebSocket server library | MIT | | Electron | Desktop app framework | MIT |
There might be more, please let us know if anything is missing, thank you!
| Example 1 | Example 2 |
|---|---|
| !Image 1 | |
How does it work?
| A.C.A.S (Tab #1) | Chess Website (Tab #2) | |----------------------|----------------------| | !A.C.A.S Tab | !Lichess.org Tab | | The engine runs on a completely different tab than the chess game page, completely isolated from it. The site cannot block the usage of A.C.A.S. | A.C.A.S sends move data via CommLink and the userscript displays the data on the board using UniversalBoardDrawer. (If "Display Moves On External Site" setting is activated!) |
If you're having issues, please visit the troubleshoot page. Developers can visit the development page. Thank you!