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Regex Tester & Debugger

Test and debug Regular Expressions visually in your browser.

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What is the Regex Tester & Debugger?

The Regex Tester executes JavaScript Regular Expressions against test strings in real-time, visually highlighting all matches, capturing groups, and reporting match indices.

Who is the Regex Tester & Debugger for?

Essential for developers writing input validation patterns, log parsing rules, and data transformation scripts.

How to Use the Regex Tester & Debugger

  1. Enter your regular expression pattern.
  2. Select flags (g, i, m).
  3. Type your test string.
  4. View live match highlighting and capture groups.

Worked Example

Pattern '\b[\w.]+@[\w.]+\.[a-z]{2,}\b' highlights email addresses in test strings.

Frequently Asked Questions

Which RegEx engine is used?

Native JavaScript RegExp — the same engine in Node.js and all modern browsers.

Does it support lookaheads and lookbehinds?

Yes. JavaScript ES2018+ supports (?=...), (?!...), (?<=...) and (?<!...).

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