Regex Tester

Test regular expressions live with highlighted matches and capture groups. Export the pattern to JavaScript, Python or Go.

How It Works

Enter a regular expression and toggle flags (global, case-insensitive, multiline, etc.).

Paste your test string and see all matches highlighted in real-time.

View capture groups, read the pattern explanation, and copy in JS, Python, or Go format.

The tool uses your browser's native JavaScript RegExp engine, which supports ES2018+ features including named groups and lookbehind.

Catastrophic backtracking can occur with nested quantifiers like (a+)+. The tool shows execution time to help identify slow patterns.

Yes. Enable the 'm' flag to make ^ and $ match line boundaries, and the 's' flag to make . match newlines.

Varstatt is a one-person product studio run by Jurij Tokarski, product engineer since 2011. These tools are free and open — no signup, no catch.