However, Crystal aims to support the lowest common denominator between POSIX and Windows, so not all of the Windows standard APIs are supported out-of-the-box. Other Windows specific libraries will need to be created specifically for Windows users/developers.
Crystal achieved basic Windows support as of 2021/11/18. https://github.com/crystal-lang/crystal/issues/5430
As of Crystal 1.5.0, Windows support is basically there. https://crystal-lang.org/2022/07/06/1.5.0-released.html
However, Crystal aims to support the lowest common denominator between POSIX and Windows, so not all of the Windows standard APIs are supported out-of-the-box. Other Windows specific libraries will need to be created specifically for Windows users/developers.