What Is Regex Tester & Debugger?

A free online regex tester and debugger. Write patterns with flags (global, case-insensitive, multiline, dotall, unicode, sticky), see live match highlighting, and inspect capture groups with match indices. All in your browser.

Why Use Regex Tester & Debugger?

  • Live match highlighting in the test string
  • Capture group extraction with group numbers
  • All six regex flags supported (g/i/m/s/u/y)
  • Match index positions and count display

How to Use Regex Tester & Debugger — Step by Step

1

Enter your regex pattern in the pattern field.

2

Toggle flags (g, i, m, s, u, y) as needed.

3

Paste your test string into the input area.

4

View highlighted matches and capture groups below.

Who Is Regex Tester & Debugger Best For?

  • pattern validation
  • data extraction
  • log parsing
  • string matching

Regex Tester & Debugger — Frequently Asked Questions

What regex flavor is supported?

The tool uses JavaScript's native RegExp engine, which supports the standard ECMAScript regex syntax.

What does the sticky (y) flag do?

The sticky flag matches only at the regex lastIndex position, not just anywhere in the string. It is useful for incremental parsing.

Ready to Use Regex Tester & Debugger?

Free online tool — works in your browser, no sign-up required. Start using it right now.

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