Checks for valid UK/British postcodes. There was another on here that had for some reason been upvoted, but it was actually incorrect as it worked on none of my valid own postcodes! Namely that it assumed two letters and a number (BS3) when you can have variations (M20). Allows for an optional spac...

1-15 alphanumeric login name

Matches any valid JSON object, matches recursively. Passes all JSON test cases I found.

From a (fairly large) list of User Agent strings, extract the OS, Browser, and Device Type.

Captures all fields from a CSV file's line. Can be customized with user-defined field separator and protecting character.

A quite neat regular expression for URLs, e-mails..., I found on Matthew O'Riordan's blog.

Matches distorted email addresses and converts them back to real ones.

The BNF rules from RFC 5322 transformed to PCRE by Nikita Popov and described in the post http://nikic.github.io/2012/06/15/The-true-power-of-regular-expressions.html.

Grabs the ID for the regex101.com permalink code. If a revision number is provided, grab that as well.