Regex Tester
Test regular expressions against your text with live match highlighting, capture groups and flags. Free and fully in your browser.
- ✓ Runs in your browser — nothing uploaded
- ✓ No sign-up
- ✓ Free, no limits
- [8] a@x.com groups: a, x
- [19] b@y.com groups: b, y
This free regex tester lets you build and check a regular expression against sample text with instant feedback. Type a pattern, toggle the i, m and s flags, and every match is highlighted directly in your text as you type, with a list of each match's position and captured groups below. Invalid patterns show a clear error instead of failing silently, so you can fix them as you go.
It uses your browser's own JavaScript regular-expression engine, which means what matches here is exactly what will match in your JavaScript or TypeScript code — no dialect surprises between the tester and production. The global flag is applied automatically so you always see every match, not just the first, and capture groups are broken out so you can confirm a pattern is extracting the right pieces before you paste it into code.
Everything runs locally in your browser; the patterns and test text you paste are never uploaded. Worked example: the pattern (\w+)@(\w+)\.com against “a@x.com b@y.com” finds two matches and captures the name and domain of each. Highlighting is rendered safely from match positions, never by injecting HTML.
Frequently asked questions
Which regex flavor does this use?
JavaScript's native RegExp engine, so results match exactly what your JS/TS code will do. It supports the i (case-insensitive), m (multiline) and s (dotall) flags; the global flag is always on so you see all matches.
How do I see capture groups?
Each match in the results list shows its captured groups in order, so you can confirm your parentheses are extracting the right substrings before using the pattern in code.
Are my pattern and test text uploaded?
No. Everything is evaluated in your browser and never sent to a server — safe for private data and internal strings.