Regex Tester

Test and debug regular expressions with live match highlighting. Supports all JavaScript RegExp flags and named capture groups.

Pattern

//gm

Flags

Test String

Match Highlights

The quick brown fox jumps over the lazy dog fox found again here

Related Tools

✓{}

JSON Validator

Validate JSON syntax and structure with detailed error reporting

✓<>

XML Validator

Validate XML documents for well-formedness and structure errors

Frequently Asked Questions

What is a regular expression?

A regular expression (regex) is a sequence of characters that defines a search pattern. They're used for pattern matching in strings, input validation, search and replace, and data extraction.

What regex flags are supported?

g (global), m (multiline), i (case insensitive), s (dotAll - dot matches newlines), u (unicode) are all supported.

How many matches can this tool find?

The tool will find up to 500 matches. For very large inputs, consider limiting the scope of your test string.

All processing happens in your browser. No data is sent to any server.