developer
Client-Side Only
Free Forever

Regex Tester & Debugger

Test and debug Regular Expressions visually in your browser.

/
/
0 Matches

Advertisement

Share this tool:

How to use the Regex Tester

Enter your RegExp pattern, apply flags (like global 'g' or case-insensitive 'i'), and type a test string. Matches will be highlighted automatically.

?Frequently Asked Questions

Related Tools

T

Text Compare

text

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 Calculation 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 (?<!...).

Explore Related Utilities & Guides

Related Tools

All Developer Tools

Text Compare

Compare two pieces of text side-by-side to spot differences.

Educational Guides

All Guides

How to Properly Format JSON Payloads for REST APIs

Learn the standard practices for organizing and nesting JSON structures for optimal API transmission and parsing performance.

Understanding Base64 Encoding: A Complete Guide

A deep dive into how binary data is translated into 64 ASCII characters for safe web transport and storage.