Testing & Debug
RegExp Tester
Test regular expressions with real-time highlighting
Build and test regular expressions against sample text with matches highlighted as you type. See capture groups, toggle flags like global and case-insensitive, and iterate quickly, so you can perfect a pattern for validation, search-and-replace, or log parsing before dropping it into your code.
Runs in your browser · AI assist is the only opt-in exception · no tracking, no ads
How to use RegExp Tester
- Enter your regular expression and choose the flags you need.
- Paste sample text to test the pattern against.
- See every match highlighted in real time.
- Refine the expression and inspect captured groups.
Frequently asked questions
Which regex flavor is used?
It uses JavaScript's regular-expression engine, so patterns behave the same as they would in browser and Node.js code.
What do the flags do?
Flags modify matching: g matches globally, i ignores case, m treats input as multiline, and s lets the dot match newlines. You can toggle them to see the effect.
Can it show capture groups?
Yes. Matches and their captured groups are displayed so you can confirm the pattern extracts exactly the parts you intend.
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