An excellent tool for regex testing is Regex Coach by Edi Weitz in Germany.  It’s makes one of the most painful coding tasks a lot less odios, thanks to real-time color-coded highlighting of matches, and a simple, intuitive interface. It’s only limitations that I’ve discovered are in character support; strangely, considering its European origins, it doesn’t support the Euro symbol “€”. That’s not likely to be a major flaw for anyone checking the regex syntax, however, and regex is an indispensible aid for that.