Edit and Test Regular expressions online using RegExr.

Regular expressions provide a powerful and flexible way to search for phrases or characters but they are also confusing and many developers find them quite daunting. If you have been reluctant to learn regular expressions because of their apparent complexity, fear no more. RegExr is for you. RegExr is a free web tool for editing and testing regular expressions. The interface of the web site is simple. You enter your regular expression in a text field and then you will need to write or copy/paste the text in the text box below to see if the text contains your regular expression or pattern.
A useful sidebar with descriptions and usage examples is provided to make it easier to learn Regular Expressions through trial and error.

There is also a desktop version available for Mac OS X, Windows and UNIX that you can download and install on your computer.