Rejex lets you craft regular expressions on-the-fly

By Erez Zukerman, Download Squad – March 11, 2010 at 02:40PM

Rejex is a very handy little site for building and testing regular expressions on the fly. It’s composed of four simple text boxes and a very informative cheat sheet (not shown above, but after the jump). You feed your text into the “Test String” box (the middle one), and then your expression into the top box, and immediately see the matches in the bottom box. Here I am searching for instances of the letter “o” which are either at the beginning or the end of a word, so I got a match for “over” but not for “fox”.

Half the tool’s value lies with the informative cheat sheet, showing you exactly what each regex character does. I would have been happy for some “popular regexes” such as “matching an email address” and “matching a US phone number” etc, but even so, this is definitely a tool I am going to bookmark for future use.

The regex cheat sheet: