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Regex Tester

Test and analyze regular expressions with live matching, explanations, and multi-language support.

Regular ExpressionNo Pattern
Test your regex patterns and view detailed explanations.
Match Results
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Regex Controls
Test your regex patterns and view detailed explanations.

• Enter a regex pattern and test content to see live matches

• Use flags to modify regex behavior (g=global, i=ignore case, m=multiline)

• Switch languages to see how the same pattern behaves differently

Regex Explanation
JavaScript - Uses V8 regex engine

Enter a regex pattern to see explanation

Quick Reference
Quick reference guide for regex tokens and patterns
.Any character except newline
\dAny digit (0-9)
\DAny non-digit
\wWord character (a-z, A-Z, 0-9, _)
\WNon-word character
\sWhitespace character
\SNon-whitespace character
[abc]Character set - matches a, b, or c
[^abc]Negated character set - not a, b, or c
[a-z]Character range - lowercase letters
[A-Z]Character range - uppercase letters
[0-9]Character range - digits

Regular Expressions Guide

Complete guide to regular expression syntax, patterns, and best practices across different programming languages.

Regular Expression Tester Guide

What is a Regular Expression?

A regular expression (regex) is a sequence of characters that forms a search pattern. It's used to match, find, and manipulate text based on specific rules. Regular expressions are supported in almost every programming language and are essential tools for developers.

Key Features of Our Regex Tester

Multi-Language Support

Test your regex patterns across different programming languages:

  • JavaScript: Browser and Node.js environments
  • PHP: Server-side web development
  • Python: Data science and web applications
  • Java: Enterprise applications
  • Rust: Systems programming
  • .NET (C#): Microsoft stack applications

Live Testing

  • Real-time pattern matching as you type
  • Instant feedback on pattern validity
  • Highlighted matches in your test content

Detailed Explanations

  • Pattern breakdown and analysis
  • Language-specific behavior notes
  • Understanding of regex components

Quick Reference

Comprehensive guide including:

  • Character classes (\d, \w, \s)
  • Anchors (^, $, \b)
  • Quantifiers (*, +, ?, {n,m})
  • Groups and capturing
  • Lookarounds and assertions

Common Use Cases

Email Validation

\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b

Phone Number Extraction

\+?\d{1,4}?[-.\s]?\(?\d{1,3}?\)?[-.\s]?\d{1,4}[-.\s]?\d{1,4}[-.\s]?\d{1,9}

URL Matching

https?:\/\/(www\.)?[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)

Password Validation

^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)(?=.*[@$!%*?&])[A-Za-z\d@$!%*?&]{8,}$

Best Practices

  1. Start Simple: Begin with basic patterns and add complexity gradually
  2. Test Thoroughly: Use various test cases to ensure your regex works correctly
  3. Consider Performance: Avoid catastrophic backtracking with complex patterns
  4. Language Differences: Be aware that regex behavior can vary between languages
  5. Escape Special Characters: Remember to escape characters that have special meaning

Regex Flags Explained

  • g (Global): Find all matches, not just the first one
  • i (Case Insensitive): Ignore case when matching
  • m (Multiline): ^ and $ match line breaks
  • s (Dotall): . matches newline characters
  • u (Unicode): Enable Unicode matching
  • y (Sticky): Match from the exact position in the string

Getting Started

  1. Enter your regex pattern in the pattern field
  2. Add any flags you need
  3. Paste your test content
  4. Select the target programming language
  5. View matches and explanations in real-time

Start with our built-in examples to learn common patterns, then experiment with your own use cases!