: Grab the extension for Chrome, Firefox, or Edge. Find a Script : Search sites like Greasy Fork or GitHub .

// ==UserScript== // @name Chess Board Highlighter // @namespace http://tampermonkey.net/ // @version 1.0 // @description Highlight last move on chess.com/lichess // @author You // @match https://www.chess.com/* // @match https://lichess.org/* // @grant none // ==/UserScript==

Once installed, Tampermonkey acts as an executor: you feed it a script, define which URLs it should run on (e.g., https://www.chess.com/* ), and the script automatically executes when you visit those pages.

GM_xmlhttpRequest( method: 'GET', url: `https://lichess.org/cloud-eval?fen=$encodeURIComponent(fen)&multiPv=1`, onload: function(res) let best = JSON.parse(res.responseText); console.log('Best move:', best.pvs[0].moves);

From a technical standpoint, these scripts are difficult to detect because they run on the client-side (the user's browser) rather than the server. However, major platforms have developed sophisticated behavioral analysis algorithms to identify patterns—such as unnatural move accuracy or consistent time intervals—that suggest a script is in use. 3. The Arms Race: Customization vs. Anti-Cheat

| 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. |

| Category | Purpose | Example | |----------|---------|---------| | | Overlay engine evaluations on the board | Show Stockfish eval bar next to each move | | Automation | Automatically play moves based on a chess engine | Auto-moving pieces to match engine top line | | Training | Highlight mistakes, show best moves after game | Auto-analyze each game on Lichess | | Interface Tweaks | Remove distractions, add clock alerts, resize board | Hide chat, auto-request rematch | | Data Mining | Collect opponent stats, opening frequencies | Show opponent's win rate with each opening |