Developer toolsFree & private
Regex tester with live match highlighting
Test JavaScript regular expressions with live highlighting, flags, capture groups, and syntax validation in a protected browser worker.
Regex tester Local processing
Live match highlighting
Capture groups
Execution timeout
How to Use
- 1
Enter a JavaScript regex pattern and flags.
- 2
Add sample text to test.
- 3
Inspect highlighted matches and capture groups.
Frequently Asked Questions
Which regex engine is used?
Your browser's JavaScript RegExp engine runs the expression inside an isolated web worker.
Why can a pattern time out?
Patterns with excessive backtracking can take a long time. The worker is stopped after one second to keep the page responsive.
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