These: regex101.com and regexper.com ! Regexper will render your regular expression as a friggin' railroad diagram!! It's extremely handy when debugging your r

These: regex101.com and regexper.com ! Regexper will render your regular expression as a friggin' railroad diagram!! It's extremely handy when debugging your regex or to understand those super complex, multiline regexes, that someone has posted to Stack Overflow. Both regular-expressions.info and rexegg.com are incredibly good explanations of Regular Expressions. regular-expressions.info is even available as a PDF e-book against a tip of your choice.