Free Online Regex Tester & Debugger
Test & highlight regex matches
About Regex Tester
Test regular expressions against sample text with real-time match highlighting. Supports JavaScript regex syntax with flags. See capture groups, match indices, and explanations.
How to Use Regex Tester
- 1
Enter your regex pattern
Type your regular expression and set flags (g, i, m, etc.).
- 2
Add test text
Paste or type sample text to test against.
- 3
View matches
Matches are highlighted in real time with capture group details.
Frequently Asked Questions
Is my data safe?
Yes. All processing happens entirely in your browser. Your data never leaves your device and is never uploaded to any server.
Which regex flavor is used?
JavaScript's built-in RegExp engine is used, which supports most standard regex features including lookahead and lookbehind.