• MRI(Matz’s Ruby Implementation)
    • Implemented in C
    • Original implementation
    • From 1.9.x onwards, incorporates YARV
  • mruby
    • Lightweight version, for embedded systems
  • JRuby
    • Implemented in Java, runs on JVM
    • Interpreter, JIT compilation (default), AOT compilation
    • Can call Java from JRuby and JRuby from Java
  • IronRuby
    • Runs on .NET
    • Can use .NET libraries
  • MacRuby
    • Before 0.5 uses YARV, after that uses LLVM
    • JIT compilation, AOT compilation
    • Runs on OSX
  • Rubinius
    • Mostly implemented in Ruby
    • JIT compilation (AOT compilation to machine code is not possible?)
    • Virtual machine for bytecode is implemented in C++
    • Bytecode to machine code uses LLVM
  • MagLev
    • Runs on Smalltalk VM
  • Cardinal
    • Runs on Parrot Virtual Machine
  • HotRuby
    • Implemented in Javascript and ActionScript
    • Runs in browser
  • Topaz
    • Written in RPython (a subset of Python)
    • Same mechanism as PyPy (Python -> machine code JIT compilation)?
  • Crystal
    • Ruby-like syntax
    • Can call C functions
    • JIT compilation, AOT compilation (machine code)