This extension runs through webpages, applying your find and replace rules. You can define rules in the extension's options page. They simply consist in : - Match : either a string or a regular expression - Replacement : either a string or a function that receives arguments (node, match), where 'node' is the DOM node in which there was a match and 'match' the result array (as returned by RegExp.prototype.exec()) So you can simply find/replace strings ('keyboard' -> 'leopard' for instance) or take it to another level and use custom functions to apply CSS to substrings, move them through the DOM and so forth. You can configure the extension through the extensions page (chrome://extensions/)