Regex Tester
Test regular expressions with live matches, flags, and instant feedback.
Match Count: 3
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About this tool
The Regex Tester lets you build and debug regular expressions against live text. Type a pattern and flags, and matches highlight instantly with capture group breakdowns — no more guessing why a pattern fails in production.
It uses JavaScript's regex engine, so behavior matches what you'd get in Node.js or the browser. Test edge cases like empty strings, unicode, and multiline input before committing a pattern to your codebase.
How to use
- 1Type your regular expression and flags (e.g. gi).
- 2Paste the text you want to test into the corpus box.
- 3Matches are listed instantly with a live match count.
Frequently asked questions
The usual suspects: unescaped special characters (., *, +, ?), forgetting the global flag for multiple matches, or greedy quantifiers consuming too much. The live highlighting shows exactly what matched, which pinpoints the issue.