A regular expression (regex, regexp or rational expression) is a sequence of characters that specifies a search pattern. Usually these patterns are used by string-searching algorithms for find or find and replace operations on strings, or for input validation.

Yes, it's completely free to use.

This RegEx Tester is powered by a Retool app, and is using an embedded app feature, allowing you to easily turn internal tools and utilities like this into public, customer-facing apps. See our other RegEx generator tool, CSV API generator, mock data API generator, and CSV app generator.