Developer tool
Test a Regular Expression
Try a JavaScript regular expression against sample text and highlight each match locally.
Runs locally in your browser
Your text is not uploaded.
Simple steps
How it works
- 01
Enter a regular expression and the text to test.
- 02
Choose flags such as global, case-insensitive, or multiline.
- 03
Review match highlighting and capture groups.
Good to know
Frequently asked questions
Which regex flavor is used?
The tester uses JavaScript RegExp syntax supported by your browser.
Can I see multiple matches?
Enable the global flag to find and highlight every match.
What happens with an invalid pattern?
The browser’s syntax error is displayed beside the tester instead of running the expression.
Can a pattern hang the page?
Patterns run in the browser; avoid catastrophic backtracking patterns on very long input.
Is test text sent online?
No. Matching runs locally in your browser.