Regex Tester

No. Matching runs entirely in your browser's JavaScript engine — neither the pattern nor the test text is ever sent to a server.

With the g (global) flag on, the tool finds every match in the text instead of stopping at the first one. With it off, only the first match found is shown.

Parts of a pattern wrapped in parentheses () are called capture groups. For example, (\d{3})-(\d{4}) splits a phone number into two parts, extracted separately as group 1 and group 2.

It uses the browser's built-in JavaScript (ECMAScript) regex engine. The syntax is mostly similar to PCRE or Python's re module, but some features — like lookbehind support — can differ.

An error message appears below the pattern box, and no match results are calculated until the pattern is fixed.