Regex Lab

Test regex patterns with real-time matching and capture group preview

Regex Testing

Enter your regex pattern to test
Enter text to test against the pattern

Settings

Quick Reference

  • . - Any character
  • * - 0 or more times
  • + - 1 or more times
  • ? - 0 or 1 time
  • \d - Any digit
  • \w - Any word character
  • \s - Any whitespace
  • [] - Character class
  • () - Capture group

Remember

  • Escape special chars with \
  • Use .*? for non-greedy
  • Test edge cases

What is Regex Lab?

Regex Lab is a testing ground for regular expressions (regex). It helps you:

  • Test regex patterns against text or CSV data
  • See live matches, positions, and capture groups
  • Validate patterns before using them in production tools
  • Learn regex syntax with immediate feedback

Step-by-Step Guide

  1. Enter your regex pattern - Use standard regex syntax
  2. Choose a mode - Python or JavaScript (note: may have slight differences)
  3. Provide test text - Paste the text you want to test against
  4. Click "Test Regex" - See matches instantly

Common SEO Regex Patterns

Use Case Pattern
Email addresses \b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b
URLs https?://(?:[-\w.]|(?:%[\da-fA-F]{2}))+
Meta title tag <title[^>]*>(.*?)</title>
Tracking parameters [?&](utm_[^&]+|fbclid|gclid)
H1 tags <h1[^>]*>(.*?)</h1>

Tips for Success

  • Escape special characters: Use \ before characters like . * + ? [ ] ( ) { } ^ $ |
  • Use capture groups: Wrap parts in parentheses () to extract specific portions
  • Test incrementally: Build your pattern step by step, testing as you go
  • Be specific: More specific patterns reduce false matches

Common Pitfalls

  • ❌ Forgetting to escape special characters (use \. not .)
  • ❌ Using greedy quantifiers (.*) when you need non-greedy (.*?)
  • ❌ Not testing edge cases (empty strings, special characters, etc.)