Regex Tester 🔒 Your data never leaves your browser.

Test patterns with live highlighting. Freeze-proof via Web Worker.

//g

gall matchesiignore casemmultiline ^$sdot matches newline

About this tool

This tester runs your pattern with the same JavaScript engine your code uses — matches here match in Node.js and every browser. Matches highlight as you type, with numbered and named capture groups listed per match.

Patterns execute in a Web Worker with a 2-second kill switch, so a catastrophically backtracking pattern like (a+)+$ cannot freeze the tab. Want a pattern library and cheatsheet too? Visit our dedicated regexcheck.com.