Regex Tester
Write a regular expression and see what it matches as you type, with capture groups, named groups and flags broken out.
//g
global — find every match, not just the first
Runs entirely in your browser — nothing you paste is uploaded or stored.
About regex tester
Regular expressions are quick to write and slow to verify. The fastest way to trust one is to watch it run against real input, which is what this does on every keystroke — including which capture groups filled in and what they caught.
It uses your browser's own regex engine, so the behaviour matches exactly what JavaScript will do with the same pattern and flags. Patterns written for other flavours (PCRE, Python, Go) mostly transfer, but lookbehind and some escapes differ.
Good to know
- Every match is listed with its index, the full matched text, and each numbered and named group — usually the fastest way to see why a group is empty.
- Flags are individually toggleable: g for all matches, i for case-insensitive, m for multiline anchors, s so a dot spans newlines, u for full Unicode, y for sticky.
- Matches are capped to keep the page responsive on a pattern that matches an empty string across a large input.