Crystal is a high-level general-purpose, object-oriented programming language, designed and developed by Ary Borenszweig, Juan Wajnerman, Brian Cardiff and more than 400 contributors.

It is released as free and open-source software under the Apache License version 2.0.

Crystal possesses a macro system and supports generics as well as method and operator overloading.

Or using an object-oriented programming style: The following code defines an array containing different types with no usable common ancestor.

In 2020, it was reported that the infotainment units in vehicles produced by Nikola Corporation were written in Crystal.