Tampermonkey Chess Script ~upd~ May 2026

Tampermonkey Chess Script: Deep Technical Write-Up

1. Overview & Purpose

A Tampermonkey script (userscript) runs in the browser, manipulating the DOM and injecting logic into a chess website’s frontend. Common features range from move highlighting and best-move suggestions (via UCI engine integration) to auto-move and premove bots.

• Chess.com Fair Play Policy → permanent ban.
• Lichess Terms of Service → account closure.

Dark modes, custom piece sets, or moving the clock to a more readable position. Square Labels: Adding coordinates directly onto the board squares. The Verdict:

4. Board Highlighter

• Function: Colors squares controlled by each piece.
• Impact: Training tool, but also assists tactical spotting during live games.

Verify: Click the Tampermonkey icon in your browser toolbar to ensure the script is listed and toggled to Enabled.

Move Reading
Using the website’s internal state (often from a global JavaScript object like LichessGround or ChessComBoard), the script extracts the current FEN (Forsyth–Edwards Notation) or PGN of the position.

Part 1: What is Tampermonkey?

Before understanding a chess script, you must understand Tampermonkey itself.