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).
If you don't remember the regex syntax, just press cmd+r or click button in the top-right. You will get the reference sheet, so you don't have to remember everything.
The user interface is very minimalistic and non-distractive. By default the color is the same as your menubar, but you can always switch to dark or light mode (see: Preferences). You can also open app in beautiful full screen mode which is perfect when you want to focus or to demonstrate regular expressions to other people.

* Expressions uses ICU regular expression standard. More information you will find here:

What’s New

Version 1.3.1

- fixed bug that appeared on macOS 10.11

Ratings and Reviews

3.2 out of 5
5 Ratings

5 Ratings

FeatureRequesterGuy ,

Feature request

Really enjoy this app. Nice not to have to use a Web app based tool .

However i would LOVE the ability to use my system font and to increase font size for the app from preferences.


Developer Response ,

It will be implemented in future versions

Schlaeps ,

Best Looking Regex App, Not Most Full Featured

This is easily the best looking regex app. The default appearance is perfect for quick construction / testing of a matching regex, but it lacks features I would expect in an app like this like a list of all capture groups, replace support, and per-expression regex options (case insensitivity, multiline, etc. are available in the preferences, but get applied globally, rather than per expression)

rysmax ,

Did not live up to expectations

I expected that the application will show different groups.
But it shows everything monolithically.
Text for example: "...1...2...3..."
Expression for example: "(?<char1>1).*(?<char2>2)"
Application result: hightlighted symbols "1...2"
Expected result: hightlighted symbols "1", "2"
PHP preg_match result: ["0" => "...1...2...3...", "char"' => "1", "char2" => "2"]
p.s. See the RegExRX for view the "ideal" visualization of result.

Developer Response ,

By default Expressions highlights the 0th group which is the whole regex.
To highlight a group, press cmd+shift+} (Menu View -> Highlight next group).


3.3 MB

OS X 10.11 or later, 64-bit processor



Age Rating


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.