Best Online Regex Tester

Free Live match highlighting · Capture groups · All flags Real-time · Group capture · Flags
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Enter a pattern above and test string below

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Why This Is the Best Regex Tester Online

Live Match Highlighting

Matches are highlighted in real-time as you type your regex pattern. See exactly what your expression captures.

Capture Groups

View all capture groups and their matched values displayed clearly below the test string.

All Flags Supported

Toggle g (global), i (case-insensitive), m (multiline), and s (dotall) flags with one click.

Match Details

See the exact index position and length of each match for precise debugging.

Frequently Asked Questions

What regex flavor does this tester use?

This tester uses JavaScript's built-in RegExp engine, which is the standard for web development and Node.js applications.

How do I test a regex for email validation?

Enter your email regex pattern like /^[\w.-]+@[\w.-]+\.[a-z]{2,}$/i in the pattern field, then type a test email in the test string area to see live matching.

Why does my regex not match across lines?

By default, . does not match newlines. Enable the s (dotall) flag to make . match any character including newlines, or use m (multiline) to make ^ and $ match line boundaries.

In-depth guide
Essential Developer Tools Guide
Regex, cron, timestamp, URL & more
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