Regex Tester Online Free

Test and validate regular expressions with live matching

What is Regex Tester?

A regex tester lets you write and test regular expressions against sample text in real-time. As you type your pattern, matches are instantly highlighted, making it easy to debug and refine your regex patterns.

Our Regex Tester supports full JavaScript regular expression syntax including flags (global, case-insensitive, multiline, dotAll). It shows match groups, captures, and provides clear feedback on pattern errors.

Whether you're writing data validation rules, parsing log files, or building text extraction patterns, this tool dramatically speeds up regex development and testing.

How to Use Regex Tester

  1. Enter your regular expression pattern
  2. Add flags (g for global, i for case-insensitive, m for multiline)
  3. Paste test text in the input area
  4. Matches are highlighted in real-time as you type

Why Use Our Regex Tester?

Frequently Asked Questions

How do I test a regular expression online?

Enter your regex pattern in the pattern field and your test string in the text area. The tool highlights all matches in real-time, showing match groups, positions, and capture groups. It supports JavaScript regex syntax with all flags (g, i, m, s).

What regex flags are supported?

The tester supports all JavaScript regex flags: g (global - find all matches), i (case-insensitive), m (multiline - ^ and $ match line boundaries), s (dotAll - dot matches newlines), and u (unicode - full Unicode support).

Can I see capture groups in my regex matches?

Yes! The tool displays all capture groups for each match, showing both named and numbered groups with their matched values and positions. This is invaluable for debugging complex patterns with multiple capture groups.

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