Think of it as a "client-side mod." When you visit a website, your browser downloads the page’s code. A Tampermonkey script intercepts that code and changes it before you see the result. It can add buttons, remove advertisements, change colors, inject data from third-party APIs, or even automate actions.

Every second, it scans the Chess.com game page for pieces with the wk (white king) or bk (black king) class and adds a red glow.

Keep scripting ethically, and may your forks be mighty. Have a favorite Tampermonkey chess script? Share it in the comments below (GreasyFork links only, please).

This article covers everything you need to know about Tampermonkey chess scripts. Before we talk about chess scripts, we need a foundation. Tampermonkey is a browser extension (available for Chrome, Firefox, Edge, Safari, and Opera) that allows you to run userscripts —small pieces of JavaScript code that modify web pages.

On the other edge, you have that destroy the spirit of the game. Using an engine via a script is no different than hiding a phone in your lap during a tournament. You gain fake ELO, but you lose the joy of improvement.

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. The Tampermonkey chess script ecosystem is a double-edged sword.