Crystal is a programming language with the following goals:

  • Have a syntax similar to Ruby (but compatibility with it is not a goal)
  • Statically type-checked but without having to specify the type of variables or method arguments.
  • Be able to call C code by writing bindings to it in Crystal.
  • Have compile-time evaluation and generation of code, to avoid boilerplate code.
  • Compile to efficient native code.


We love Ruby's efficiency for writing code.

We love C's efficiency for running code.

We want the best of both worlds.

We want the compiler to understand what we mean without having to specify types everywhere.

We want full OOP.

Oh, and we don't want to write C code to make the code run faster.


  • The project is in alpha stage: we are still tweaking the language and standard library.
  • The compiler is written in Crystal.


Follow these instructions

Try it online




Questions or suggestions? Ask in our Google Group, join our IRC channel #crystal-lang at chat.freenode.net, ask on our Gitter channel or ask on Stack Overflow under the crystal-lang tag.


Read the general Contributing guide, and then:

  1. Fork it ( https://github.com/crystal-lang/crystal/fork )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request

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Licensed under the Apache License, Version 2.0.