OpenTK, also known as The Open Toolkit library, is a C# graphics library superseding the Tao Framework.^[1] It provides access to graphics tools contained in OpenGL, OpenCL, and OpenAL to a variety of CLR-based languages (C#, F#, etc.).^[2] Particularly, it is usable with any language utilizing either of the .NET Framework or Mono frameworks^[3] for versions prior to 4.0 and .NET Core 3.1 and up, continuing with .NET 5, for major version 4.