Developer tools
Regex Tester
Test JavaScript regular expressions with live highlighting and group breakdown.
//g
2 matches
Email me at hi@toulino.app or sales@example.com
“hi@toulino.app” at index 12
“sales@example.com” at index 30
How it works
- 1Type a pattern and (optionally) toggle flags.
- 2Paste the text you want to test against.
- 3See matches highlighted live; expand each match to inspect groups.
Use cases
- Build a regex for input validation.
- Audit which strings match an existing pattern.
- Learn capture groups visually.
Frequently asked questions
Which regex flavor?
JavaScript ECMAScript regex (same engine as your browser). PCRE features like recursion are not supported.
Why is global mode (g) on by default?
For most testing you want to see every match. Switch it off to test a single-match pattern.
Does it support lookbehind?
Yes — modern V8/SpiderMonkey support both lookahead and lookbehind, fixed and variable width.
Read the guide
How to test a regex without copy-pasting into your editor
A regex tester is a debugger for patterns. Here is a workflow that produces a regex you can trust on the first paste.