Regexes are very specific text tools. They can do a lot of heavy lifting that would, otherwise, take thousands of LOC, and perhaps wouldn't reach the same result.

They are fast (relatively fast) and trustworthy. Well, kinda of. Regexes are so hard to understand at first, that even minor details can lead to hours of endless try/fail circle.

To speed up the process, there is a website (there are similar websites for different regex syntaxes) that you can try your regex against a sample text, and it will give you full results.

Here's the compilation:

Python

• http://re-try.appspot.com/ (very good, my personal favorite);
• http://www.pythonregex.com/

csharp

• http://regexhero.net/tester/ (very pretty, but untested, uses silverlight);
• http://www.radsoftware.com.au/articles/regexlearnsyntax.aspx (desktop tool, already used. It's simple, but powerful);
• http://www.ultrapico.com/Expresso.htm

java

• http://www.regexplanet.com/advanced/java/index.html (I'm not a Java, it's just here for completeness)

Do you guys recomend other tools?