Regex is a regular-expression testing tool that is easy to use.
- Immediate feedback. Dynamic highlighting of matches as you modify the regular expression or sample text
- Automatic escaping of special characters when copying a regular expression
- Automatic unescaping of special characters when pasting a regular expression
- Supports capture groups
- Supports matching options such as case-insensitive matches
- Supports positive lookahead, negative lookahead
- Supports positive lookbehind, negative lookbehind
- Supports backreferences
- Fast and dead-simple to use
See the regular expressions tutorial at http://motionobj.com/articles/regex-macos-tutorial.