Regex Tester

Regex Tester

/ / g
0 chars
Matches
Enter a regex pattern to see matches
Flags: g
Pattern: (empty)

What are Regular Expressions?

Regular expressions (regex or regexp) are patterns used to match character combinations in strings. They are powerful tools for text processing, validation, and manipulation. Regex is supported in virtually all programming languages and is essential for tasks like form validation, search and replace, and data extraction.

How to Use Regex Tester

  1. Enter your pattern - Type your regular expression in the pattern field
  2. Add test text - Paste the text you want to test against in the input area
  3. Set flags - Enable flags like 'g' (global), 'i' (case-insensitive), 'm' (multiline)
  4. View matches - Matches are highlighted in real-time with match count

Regex Tester Features

  • Real-time matching - See matches as you type your pattern
  • Match highlighting - Visual indication of matched text
  • Flag support - Enable global, case-insensitive, and multiline modes
  • Match details - View all matches and captured groups
  • Error handling - Get clear error messages for invalid patterns
  • Replace mode - Test find-and-replace operations

Frequently Asked Questions

What regex flavor does this tool use?

This tool uses JavaScript's regular expression engine, which is based on the ECMAScript standard. It supports most common regex features including lookahead, lookbehind (in modern browsers), and named capture groups.

What are regex flags?

Flags modify regex behavior: 'g' (global) finds all matches, 'i' (case-insensitive) ignores case, 'm' (multiline) makes ^ and $ match line starts/ends. You can combine multiple flags.

Why is my regex not working?

Common issues include unescaped special characters, incorrect character classes, or missing flags. The tool shows error messages for invalid patterns. Start simple and build up your pattern incrementally.