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Regex Tester

Text Tools

Test and debug regular expressions with live matching and replace functionality

Common Patterns

About Regular Expressions

100% Client-Side & Private: All regex testing happens locally in your browser. Nothing is sent to any server.

What are Regular Expressions? Regular expressions (regex) are patterns used to match character combinations in strings. They're powerful tools for text processing, validation, and search operations.

Flags Explained:

  • g (global): Find all matches rather than stopping after the first match
  • i (case insensitive): Match letters regardless of case (A and a are treated the same)
  • m (multiline): ^ and $ match the start/end of each line, not just the whole string
  • s (dot all): . matches any character including newlines
  • u (unicode): Treat pattern as a sequence of unicode code points
  • y (sticky): Match only from the index indicated by the lastIndex property

Capture Groups: Use parentheses () to create capture groups. In replace mode, reference them with $1, $2, etc.

Common Metacharacters:. (any char), * (0+ times), + (1+ times), ? (0 or 1 time), ^ (start), $ (end), [] (character class), () (group)

Use Cases: Form validation, text search and replace, data parsing, log analysis, URL routing, syntax highlighting, data extraction.

AL

Ashley Leslie

Senior Software Developer

I identify complex business challenges and engineer innovative solutions that transform operational efficiency and drive measurable results.

Solving problems through strategic thinking and technical excellence.

Made with ❤️ in Germany

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