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


Neat regex application

I dabble with regular expressions now and again - impressed by their power, but frustrated by the difficulty of tweaking them to do what I want. While there have been other applications that have tried to do what Oyster does, they have either had awkward interfaces or been rather limited in their scope. Oyster makes it easy to see what is happening, has a good set of help and lets you easily save your regular expressions as pearls.

You can also download pearls from the Oyster Farm, giving you an insight into how to write more complex expressions.

You'll probably still need a book or a good website to help you get to grips with regular expressions, but with Oyster to help this becomes a much less daunting prospect. I'd definitely recommend it.


Very slick

I agree entirely with Curlypaws' review. Oyster succeeds where similar apps I've looked at have failed.

The help files are clear and concise, and the way it displays matches as you modify your pattern makes creating long patterns a pleasure.

Finally, the ability to copy the match pattern to the clipboard in a choice of programming language idioms is very useful - especially for Obj-C.


No way to view matching groups!!

No way to view matching groups, which renders it absolutely useless for all but the most basic of regular expressions.

… deleted …

refund time.


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

    Up to six family members will be able to use this app with Family Sharing enabled.

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