What regex flavor does this use?

This tool uses JavaScript's built-in RegExp engine, which supports ES2018+ features including named groups, lookbehind assertions, and the dotall (s) flag.

What do the flags mean?

g (global) finds all matches, i (case insensitive) ignores case, m (multiline) makes ^ and $ match line boundaries, s (dotall) makes . match newlines.

Can I use named capture groups?

Yes. Use (? pattern) syntax. Named groups will appear in the match details.

Is there a regex cheat sheet?

. matches any character, \d matches digits, \w matches word characters, \s matches whitespace, * is 0+, + is 1+, ? is 0 or 1, {n} is exactly n, [abc] is character class, ^ is start, $ is end.

Regex Tester

Test regular expressions with real-time matching and highlighting. Supports all JavaScript regex features.

Pattern

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

Test String

What Is a Regular Expression?

A regular expression (regex) is a sequence of characters that defines a search pattern. It is used for string matching, validation, find-and-replace, and data extraction in virtually every programming language.

Frequently Asked Questions

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