Useful regex resources

Today I want to post a list of regex resources that have been useful for me. In the first time I haven’t read a regex book, I found all my knowledge on-line, and there is plenty of regex information out there.

On-line resources

As example, because those languages provide good documentation and because I know them best, here the regex docs for Perl and C#. Especially the Perl tutorials can be recommended also to regex learners of other languages, just ignore the, by your language not supported, advanced parts.


  • perlrequick, Perl regular expressions quick start, a tutorial that gives a basic regex understanding.
  • perlretut, Perl regular expressions tutorial. A really extensive tutorial going into all details of Perl regexes.
  • perlre, the Perl regex module documentation.


Online Regex Tester

  • Regexr, my favourite one. Based on Flex, supports lookahead and fixed length lookbehind. Has also a regex community library and explain regex constructs. It is also possible to create permanent links to solutions.
  • Rubular, based on Ruby, allows also to create permanent links.
  • Regular Expression Analyzer, give it a regex and it will analyze it
  • Refiddle, you can choose the regex engine (JavaScript, Ruby, .NET)


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