Regular expressions are a powerful tool for developers, but they aren't the easiest things to build and debug. Oyster helps you interactively build and test them, storing each "pearl" in an easy to access library.

With powerful syntax highlighting, dynamic updates of matches and the results of replacement patterns in test text it has never been easier to build and test your regular expressions.

Once you've got it just the way you like it, oyster lets you copy the code in one of 11 languages onto the clip-board or by dragging out the pip into your desired editor. Starting with Dash 1.8.5 (coming August 2013) you can even save your regular expression as a snippet in Dash's library.

You're not alone either, Oyster has built in integration with Oyster Farm, an online repository for pearls. You can download something that seems to fit the bill for you, and tweak it into what you would like. You can even share your changes, or entirely new pearls of your own.

Key features:
• Keep a library of regular expressions, match tests, and replacement patterns (locally or in iCloud)
• Download and share pearls in the oyster farm
• Interactive highlighting of regular expression, matches, and pattern application
• Match highlighting includes group matches within overall match
• Generate code many languages including C#, Java, JavaScript, JSP, Objective-C (NSRegularExpression and NSPredicate), PHP, Ruby, Pearl, Python, and TCL/TK
• Handy Regex Reference sheet to help you tune your regular expression

What’s New

Version 1.4

Greatly improved the feedback on matches and sub-groups. Oyster now highlights the whole match, and all sub-groups (and sub-sub-sub groups etc) much more clearly.

Ratings and Reviews

3.0 out of 5
6 Ratings
6 Ratings
Usethes ,

Named groups doe not work at all

I'd love to use this app more, but 90% of my regex needs revolve around created named groups, which do not appear to work in this application. The help documentation shows how to do a named group, but my regex completely breaks when they are implemented. Same regexes work fine in Patterns.

TK112358 ,

I want to give this 5 stars but I can’t!

I can’t give it 5 stars because the delete library button has causted me to lose hours of work. It’s in a HORRIBLE spot and there’s no confirmation! Also, why doesn’t the app tell you how many hits you have? Odd. Good job on it in general but some obvious things have been overlooked in my opinion.

graveltech ,

Confusing and not very useful

I've used a few of these kind of apps (RegExhibit, RegExRX, etc) and this is probably the worst value for the money.

The whole app is a clunky UX nightmare. It's got a ton of features that are unclear how to use and provide little feed back. Even simple things like determining if a regex valid aren't obvious. The color changes but is the bright color valid or invaid?

What's the language selection supposed to do? It doesn't seem to matter what you pick so it comes off like a gimic… Is it copying to the clipboard? Syntax highlighting? I've got no idea and there's no feedback.

The tests bit could be useful as a way to track test cases but they don't take the step of letting you see the effect of changes wihtout selecting each one.


Red When Excited Ltd
4.8 MB
Developer Tools
OS X 10.9 or later, 64-bit processor
Age Rating
Rated 4+
© RED When Excited Ltd


  • Family Sharing

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