Code Tool
Regex Tester
Test and debug regular expressions in real-time. Includes common pattern shortcuts for email, phone, and more.
Quick Patterns
Characters: 0
Enter a regex pattern and test string to see results
Frequently asked questions
Everything you need to know about the Regex Tester.
Is this regex tester free to use?
Yes. The Regex Tester is completely free, requires no account or sign-up, and runs entirely in your browser.
Which regex flags are supported?
The tester supports the four most common JavaScript flags: g (global), i (case-insensitive), m (multiline), and s (dot-all). Toggle them with the checkboxes on the left and the active flags are shown below the pattern input.
Does it show capture groups?
Yes. Every match displays its character position in the test string, and each capture group (Group 1, Group 2, and so on) is listed separately under the match — including empty groups.
Does the tester support lookahead and lookbehind?
Yes. Matching uses your browser's native JavaScript RegExp engine, so lookahead (?=...), negative lookahead (?!...), lookbehind (?<=...), and other standard ECMAScript syntax behave exactly as they do in your browser's console.
Are my patterns and test strings sent to a server?
No. Everything is processed locally in your browser. Your pattern, flags, and test string are only saved to your browser's localStorage so your settings persist between visits — nothing is uploaded anywhere.