Never open a live game page with such a script active unless you intend to cheat.
This is the controversial side of userscripting. Malicious scripts act as a "bridge" between the browser and a local chess engine:
In the vast digital ecosystem of online chess, platforms like Chess.com, Lichess.org, and Chess24 have become battlegrounds for millions of players. Alongside this growth, a quiet arms race has emerged—not of opening theory or endgame technique, but of browser automation. At the center of this trend is a powerful browser extension called Tampermonkey, and the scripts designed to interact with chess websites: Tampermonkey chess scripts.
If you’ve ever searched for ways to automatically move pieces, analyze positions in real-time, or even train against computer-assisted play, you’ve likely encountered this term. But what exactly is a Tampermonkey chess script? Is it cheating? Can it be used legitimately? And how do you install and run one safely? tampermonkey chess script
This article provides a comprehensive deep dive into Tampermonkey chess scripts—how they work, what they can do, the legal and ethical boundaries, and step-by-step instructions for responsible use.
We are entering a new era: LLM-powered chess scripts.
Imagine a Tampermonkey script that does not use Stockfish, but uses a local AI model (like GPT-4o-mini or Llama 3) to give natural language advice. Never open a live game page with such
Example: Instead of an arrow, a small text bubble appears: "Your bishop is pinned to the king by the rook. Consider moving the queen to defend."
This is not engine evaluation—it’s positional understanding. Current fair play policies do not explicitly ban natural language advice, but they likely will. The line between "assistance" and "coaching" is blurry.
| Platform | Stance on Scripts |
|----------|-------------------|
| Chess.com | Strictly prohibits any use of external assistance during games. Automated scripts lead to permanent bans and rating reset. |
| Lichess.org | Bans engine use during play. Allows API bots if clearly marked as BOT. Tampermonkey scripts evading detection are illegal. |
| Chess24 (now merged) | Similar to Chess.com – any automation is a violation of TOS. | This is the controversial side of userscripting
You can either:
Local Stockfish via Web Worker:
let stockfish = new Worker('https://cdn.jsdelivr.net/npm/stockfish.js/stockfish.js');
stockfish.onmessage = function(e)
if (e.data.startsWith('bestmove'))
let bestMove = e.data.split(' ')[1];
makeAutoMove(bestMove);
;
function getBestMove(fen, depth=18)
stockfish.postMessage(`position fen $fen`);
stockfish.postMessage(`go depth $depth`);
Simple panel (HTML div) with buttons to enable/disable features.
In the world of online chess, the line between human intuition and computer precision is a constant battleground. While dedicated chess engines like Stockfish have been the gold standard for analysis, a subculture of "userscripting" has emerged, utilizing tools like Tampermonkey to alter the way the game is played and analyzed in the browser.
Whether you are a developer looking to automate tasks or a player curious about the technology behind "browser cheats," here is a deep dive into the world of Tampermonkey chess scripts.