Regex Tester

A regular expression is a sequence of characters that defines a search pattern. Regex is used for pattern matching in strings, such as validating email addresses, finding phone numbers, or extracting data from text.

This tool supports common JavaScript regex flags: g (global - find all matches), i (case-insensitive), m (multiline - ^ and $ match line breaks), s (dotall - . matches newlines), and u (unicode support). You can combine multiple flags.

Enter your regex pattern in the pattern field and sample text in the text field. The tool will highlight matches in real-time and show detailed information about each match, including captured groups. Toggle flags to see how they affect the results.

Captured groups are parts of a regex pattern enclosed in parentheses. They allow you to extract specific portions of matched text. For example, in the pattern (\d+)-(\d+), the two groups would capture numbers before and after the hyphen.

Yes! This tool supports all JavaScript regex features, including lookaheads, lookbehinds, quantifiers, character classes, and more. However, very complex patterns with many matches may be limited to 1000 matches to prevent performance issues.

Yes, the tool validates your regex pattern in real-time. If the pattern is invalid, you'll see an error message explaining what's wrong. Valid patterns will show matches and highlights in the sample text.