Regex Tester
Regex Tester — test regular expressions online in your browser.
- Runs in your browser
- Free, no signup
Flags
Your files are processed locally in your browser and are not uploaded to our server.
Use the regex tester to validate patterns, inspect matches and debug flags without sending your data anywhere.
Everything works in the browser with JavaScript’s native RegExp engine, so you can test patterns on real text immediately.
How to use this tool
- Type a pattern and choose the flags you want to test.
- Paste or type the text you want to match.
- Review each match, capture group and match index in the results panel.
Frequently asked questions
Does this send my text to a server?
No. Regex evaluation runs in your browser using the native JavaScript engine, and nothing is uploaded or stored.
Does it support flags like g, i, m and d?
Yes. The tester covers the JavaScript RegExp flags that are supported in modern browsers.