JRuby, YARV, Rubinius, and IronRuby are some of the alternative implementation of the Ruby language as of 2008 with each of them taking a diverge approach.
•JRuby – One of the strong features of JRuby is its capacity to invoke the classes of the Java Platform considering that it is a Java implementation of the Ruby and is closely incorporated with Java.
•YARV – an acronym for Yet Another Ruby VM, it is a bytecode interpreter developed for the Ruby programming language with the goal of trimming down the execution time of Ruby programs
•Rubinius – it is clean, understandable code that is easy for users to comprehend and extend. It is a virtual machine and compiler for Ruby.
•IronRuby – an approaching implementation of the Ruby programming language that targets Microsoft .Net framework