About this regex tester

Type a regular expression and test text — matches are highlighted instantly as you type. The table below lists each match with its position and captured groups (numbered $1, $2… and named (?<name>…) groups). A replacement field shows a live preview of String.replace() with your pattern, including group references.

The tester uses the browser's native JavaScript RegExp engine, so behaviour matches what you'll get in Node.js and front-end code. Supported flags: g (global), i (ignore case), m (multiline) and s (dotAll). Everything runs client-side — your text never leaves the browser. Related tools: Find & Replace and Text Diff Checker.