With The Regex Coach you can experiment with (Perl-compatible) regular expressions interactively. It shows whether a regular expression matches a particular target string. It can also show which parts of the target string correspond to captured register groups or to arbitrary parts of the regular expression. It can "walk" through the target string one match at a time. It can simulate Perl's split and s/// (substitution) operators. It can single-step through the matching process as performed by the regex engine. Everything happens in "real time": as soon as you make a change somewhere in the application all other parts are instantly updated. Further, The Regex Coach tries to describe the regular expression in plain English and it can show a graphical representation of the regular expression's parse tree.