Regex Tester

Test regular expressions with live highlighting and match details.

Presets:

Regular Expression

Global (g)Case insensitive (i)Multiline (m)Dotall (s)

Test String

Replace mode

About This Tool

Test and debug regular expressions with live syntax highlighting. See every match with its position, use common presets for emails, URLs, and phone numbers, and test replacements with capture group references.

This regex tester uses JavaScript regex syntax. All processing happens in your browser — nothing is sent to any server.

Frequently Asked Questions

Which regex flavor does this use?

This tool uses JavaScript (ECMAScript) regular expressions, which are supported by all modern browsers, Node.js, and many other languages.

What do the flags mean?

g = find all matches (not just the first), i = case-insensitive, m = treat ^ and $ as line boundaries, s = make . match newlines too.

How do I use capture groups in replacements?

Use $1, $2, etc. to reference captured groups. Named groups use $<name>. $& inserts the entire match. $` and $' insert text before/after the match.