Is my data sent anywhere?

No. Everything runs in your browser on this device, so it is safe for private data, API responses and tokens.

Why did my pattern stop?

Some patterns, like (a+)+ on long text, take extremely long to fail. The tester runs them separately and stops them after 1.5 seconds so the page stays responsive.

Regex tester

Try a regular expression against sample text.

How to use it

Type the pattern and pick options.
Paste the text to test.
See matches highlighted, with groups in the table.

Opening the tool…