MacRuby is a discontinued implementation of the Ruby language that ran on the Objective-C runtime and CoreFoundation framework under development by Apple Inc. which "was supposed to replace RubyCocoa".

[2] It targeted Ruby 1.9 and used the high performance LLVM compiler infrastructure starting with version 0.5.

MacRuby supported Interface Builder and shipped with a core library called HotCocoa to simplify Cocoa programming.

[3] In May 2012, Laurent Sansonetti announced RubyMotion, a port of MacRuby for iOS, OS X and Android.

[7] Version 0.2 was released in June 2008, and implemented Ruby strings, arrays and hashes as native Cocoa types.