Regex Tester
Test a regular expression against sample text with live match highlighting and capture groups. Uses the JavaScript regex engine. Free, in your browser.
Test a regular expression
Enter a pattern and sample text. Matches highlight live.
What this regex tester does
Common use cases
- 1Writing and debugging a regex
- 2Testing a pattern before coding
- 3Extracting data from text
- 4Validating input formats
- 5Learning regular expressions
- 6Checking capture groups
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About regular expressions
Regular expressions (regex) are compact patterns for matching text — finding emails, validating formats, or extracting fields. They are powerful but easy to get subtly wrong, so testing against real samples is essential.
This tester uses your browser's own JavaScript regex engine, so behaviour matches what your JS code will do. Enter a pattern and flags (like g, i, m), and it highlights every match and lists capture groups. Everything runs locally.
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Got Questions? We Have Answers.
Which regex engine does it use?
Your browser's own JavaScript engine, so behaviour matches what your JS code will do. Supports flags like g, i, m, s and u.
Does it show capture groups?
Yes. Each match lists its capture groups, and matches are highlighted in the text.
Is my text uploaded?
No. Testing runs entirely in your browser.
Does it handle global and empty matches?
Yes — it iterates safely, avoiding infinite loops on empty matches.