Vulkan!

Microsoft DirectX is a collection of application programming interfaces (APIs) for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms.

WebGL is a cross-platform, royalty-free web standard for a low-level 3D graphics API based on OpenGL ES 2.0, exposed through the HTML5 Canvas element as Document Object Model interfaces. Developers familiar with OpenGL ES 2.0 will recognize WebGL as a Shader-based API using GLSL, with constructs that are semantically similar to those of the underlying OpenGL ES 2.0 API. It stays very close to the OpenGL ES 2.0 specification, with some concessions made for what developers expect out of memory-managed languages such as JavaScript. »

GLFW is an Open Source, multi-platform library for OpenGL, OpenGL ES and Vulkan development on the desktop. It provides a simple API for creating windows, contexts and surfaces, receiving input and events.

Python bindings for OpenGL API.

OpenGL is a great environment for developing portable, platform independent, interactive 2D and 3D graphics applications. The API implementation in Python is cumbersome, resulting in applications with high latency. To solve this problem we have developed ModernGL, a wrapper over OpenGL that simplifies the creation of simple graphics applications like scientific simulations, small games or user interfaces. Usually, acquiring in-depth knowledge of OpenGL requires a steep learning curve. In contrast, ModernGL is easy to learn and use, moreover it is capable of rendering with the same performance and quality, with less code written. »

Crystal Space is a mature, full-featured Software Development Kit (SDK) providing real-time 3D graphics for applications such as games and virtual reality. It is free (LGPL) and cross-platform (Windows, GNU/Linux, Mac OS X).