It lets you build and debug regular expressions with instant match highlighting against your own test text, so you can see exactly what your pattern matches as you type.

You can toggle common flags such as global and case-insensitive matching and watch how they change the results in real time.

It uses standard JavaScript regular-expression syntax — the same engine browsers use — so your patterns behave just as they would in your code.

Yes — matching runs entirely in your browser, so your patterns and test text are never sent to a server.