Crystal is a general-purpose, object-oriented programming language designed and developed by Ary Borenszweig and Juan Wajnerman and over one-hundred listed contributors. Crystal is developed as open source software (under the Apache License, Version 2.0) with syntax inspired by Ruby. The language is statically type-checked but does not require that the type of variables or method arguments be specified. This is the result of advanced global type inference. The language is in an active development phase.