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Regex Tester Guide

The Regex Tester is an interactive tool that helps you build, test, and understand regular expressions.

Features​

  • Live regex matching with instant feedback
  • Common pattern library for quick reference
  • Advanced mode with capturing groups and performance metrics
  • Interactive cheat sheet for regex syntax

Using the Tool​

Basic Mode​

  1. Enter your regex pattern in the pattern input
  2. Add your test string in the text area
  3. See matches highlighted in real-time
  4. Use the common patterns library for quick starts

Advanced Mode​

  1. Enable advanced mode to see:
    • Capturing groups
    • Match indices
    • Execution time
    • Multiple flag options (g, i, m, s, u)

Common Use Cases​

  • Email validation
  • URL parsing
  • Phone number formatting
  • Date validation
  • Text extraction

Tips and Best Practices​

  1. Start simple and build up gradually
  2. Test with various input cases
  3. Consider performance for large inputs
  4. Use capturing groups to extract specific data
  5. Pay attention to greedy vs. lazy matching