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Regex Tester Online - Test Regular Expressions

Test and debug regular expressions with real-time highlighting, capture groups, and replacement preview. Includes a library of common regex patterns.

🔍 Regex Pattern

📝 Test String

✨ Highlighted Matches

🔍

Matches will be highlighted here

🔄 Replace

Test regex replacement. Use $1, $2, etc. to reference capture groups.

📚 Common Patterns

✨ Real-time Highlighting

See matches highlighted instantly as you type. Visual feedback helps you understand what your regex is matching.

📦 Capture Groups

View all capture groups for each match. Perfect for debugging complex patterns with multiple groups.

📚 Pattern Library

Quick access to common regex patterns for emails, URLs, phone numbers, and more. Start with proven patterns.

Free Online Regex Tester Tool

Test and debug regular expressions with our free online regex tester. Real-time highlighting, capture group visualization, and replacement preview make it easy to build and validate regex patterns for any use case.

What are Regular Expressions?

Regular expressions (regex) are powerful patterns used to match and manipulate text. They provide a concise way to search, validate, and transform strings in programming languages, text editors, and command-line tools.

Regex Flags Explained

  • g (global): Find all matches instead of stopping after the first match
  • i (case insensitive): Match both uppercase and lowercase letters
  • m (multiline): ^ and $ match start/end of each line, not just start/end of string
  • s (dotAll): . matches newline characters

Common Use Cases

  • Validate email addresses and phone numbers
  • Extract URLs and links from text
  • Parse log files and structured data
  • Find and replace text patterns
  • Validate user input in forms
  • Extract data from HTML and XML
  • Clean and format text data

Privacy & Security

All regex testing happens locally in your browser. Your patterns and test strings never leave your device, ensuring complete privacy and security. No server-side processing, no data storage, no tracking.