RegEx Knife is an easy and useful tool for working with Regular Expressions.  RegEx Knife is unique in how it allows you to highlight capture groups within a Regular Expression, edit them and immediately see the results. RegEx Knife also makes it easy to experiment with regular expression substitutions.

Version 2 retains the simplicity of the original RegEx Knife, with the added advantage that it works on your iPhone as well as your iPad.

What’s New

Version 2.0.1

This maintenance release addresses a series of iOS 12 compatibility issues and adds support for named regex capture groups (made possible by improvements to the Regular Expression engine included in iOS 11).

Ratings and Reviews

4.1 out of 5
10 Ratings

10 Ratings

OurBigAdventure ,

Nice and Simple

I like this app, it's simple and easy to use. It is exactly what I needed to store my regular expressions and as a bonus it allows me to also store test content to help me remember what the expression does in case the title I create isn't clear in the future.

The only issues I discovered are the list not refreshing properly when adding a new empty expression and I can't figure out what the substitution template is for. Other than those simple things this app is awesome!

Anna Vashka ,

Great tool

I have been using this for years and it has been so helpful and easy that I just took it for granted and never wrote a review. A great way to test and store regex.

Good Thom ,

Needs an update

I like a lot of what this app is going, especially things like group highlighting. Unfortunately, on my iPhone X running iOS 11.4, the regex field is hidden by the header, which makes it pretty much impossible to use.


Mark Alldritt
3.8 MB

Requires iOS 8.0 or later. Compatible with iPhone, iPad, and iPod touch.



Age Rating


  • Family Sharing

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

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