Javascript Regex Tester

Test a regular expression against a string with live match highlighting.

100% private, runs in your browser

Pattern

Flags

Test string

4 matches

Bytelify is a set of Free Developer Tools.

Highlights every match live as you type, using JavaScript's own RegExp engine (the exact engine your code will run with). Runs entirely in your browser; nothing you type is sent anywhere.

What is Javascript Regex Tester?

Type a pattern and a test string and see every match highlighted instantly, using JavaScript's own RegExp engine — the exact engine your code will actually run with, not an approximation.

FAQ

All of JavaScript's regex flags — g, i, m, s, u, y — type them directly into the flags field.

A pattern that can match an empty string (like `a*`) could otherwise loop forever finding "matches" at the same position; this tool stops there rather than hang.