Compatibility: OS X 10.11 or later 64-bit

Expressions allows to play with regular expressions*. Just type your pattern and some text to test it. All the changes are updated while you're typing text or pattern. App highlights the syntax, so the pattern is easy-to-read and modify. If you use subexpressions (groups), you can highlight them by pressing cmd+shift+] (or [ – for decreasing the highlighted group number).

Homepage: http://www.apptorium.com/products/expressions