Regular Expression Tester and Debugger
Description
Test and debug regular expressions with live matching, replacement, and syntax highlighting. Supports flags and capture groups for precise pattern validation.
About Regular Expression Tester and Debugger
Test and debug regular expressions interactively, with live match highlighting as you type your pattern and test string. It uses the JavaScript regex engine running directly in your browser, so patterns behave exactly as they would in JS code and nothing is sent anywhere. Toggle flags and inspect capture groups to refine a pattern before pasting it into your project.
How to use
- Enter your regular expression pattern in the pattern field.
- Set the flags you need, such as g (global), i (case-insensitive), or m (multiline).
- Paste the text you want to test against.
- Review the highlighted matches and inspect any capture groups.
- Adjust the pattern until it matches exactly what you intend.
Examples
| Example | Input | Output |
|---|---|---|
| Match digit sequences | pattern: \d+ text: abc123 | matches: 123 |
Frequently asked questions
Which regex engine does this use?
It uses the JavaScript regex engine in your browser, so behavior matches RegExp in JS environments like Node.js and the browser.
Which flags are supported?
Common flags are supported, including g for global matching, i for case-insensitive matching, and m for multiline matching.
Can I see capture groups?
Yes. Matches are highlighted live and you can inspect the capture groups extracted from each match.
Does my pattern or test text leave my browser?
No. Matching runs entirely client-side, so your pattern and test text stay on your device.