Administration and development

Regex tester

Test a regular expression on your text and see the matches, groups, and a replacement preview.

Text to test

My server has IP 192.168.1.10 and the router is 192.168.1.1.
Outside this network: 8.8.8.8 and 1.1.1.1.

Matches highlighted

Replace with (optional, with $1, $2 and $&)

Result of the replacement

What does this mean?

A regular expression (regex) describes a pattern in text, for example "a number of one to three digits". A dot . is any character (write \. for an actual dot), \d is a digit, + is "one or more", ( ) creates a group that you see again in the matches. The options: g all matches, i case sensitivity off, m line start and end, s dot also counts for a new line, u Unicode.

This works with the regex variant of JavaScript. In other languages (such as grep or Python) details may differ. A very complex expression can briefly freeze your browser; just refresh the page if that happens.