[WestCoastJustin]

http://rubular.com/ is also really great! I use it often when programming ruby regular expressions. Fill in a batch of test strings into the box, then run your regular expression against it, and instantly see (visually) what is happening. This is a BIG plus coming from perl regex 10 years ago ;) This is not a dig a perl regex, but I just remember it was a trial and error loop, where I would continually be iterating the script to see if it worked, where as with this webpage, you just iterate, more quickly.

They also have a great example:

  test string:
  Today's date is: 9/28/2013.

  regex:
  (?<month>\d{1,2})\/(?<day>\d{1,2})\/(?<year>\d{4})

  result:
  month	9
  day	28
  year	2013

Screenshot here: http://i.imgur.com/ixyHRde.png

[VeejayRampay]

Looking at regex101, the layout of the page looks awfully similar. It seems that the author took Rubular and made it more generic. So yeah, props to Rubular.