Question 1

What regex flavor does this tool use?

Accepted Answer

This tester uses JavaScript's native RegExp engine — the same engine that runs in Node.js and every modern browser. It supports standard regex syntax plus JavaScript-specific features like named capture groups, lookaheads, lookbehinds, and Unicode property escapes with the u flag.

Question 2

How do I test a regex for email validation?

Accepted Answer

Open the Patterns library and select Email Address — it loads a ready-made pattern and sample test string. Or type your own pattern in the regex field and paste a list of email addresses in the test string area. Matches highlight in real-time as you type.

Question 3

How do I use capture groups and backreferences?

Accepted Answer

Wrap parts of your pattern in parentheses to create capture groups. The match results panel shows each group value. In Replace mode, reference them with $1, $2, $3 in the replacement field.

Question 4

Can I share my regex with someone?

Accepted Answer

Yes. Click the Share button to copy a URL that encodes your pattern, flags, and test string as query parameters. Anyone who opens that link will see your exact regex setup. No account or login is required.

Question 5

Is my test data sent to a server?

Accepted Answer

No. All regex matching runs entirely in your browser using the native JavaScript RegExp API. No data is sent to any server.

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