OBS Studio 32.1.1: OBS is free, open source video recording and editing software.
It is open source and cross platform (Windows, Mac, Linux). It can record video, and stream everything that happens on your computer screen.

It is written in C and C++, and uses all known and unknown streaming services of our time: Twitch.tv, Youtube/Youtube Gaming, hitbox, beam.pro, Daily Motion, Livecoding.tv, Web.Tv, and many others still.
Of course, it can also be used to record on video what is happening on your computer screen, even if you are playing a game.
It takes advantage of DirectX 11 capabilities but you can also configure it for OpenGL.
For video encoding, it uses, among other things, codec capabilities such as the x264 free software library, Intel Quick Sync Video and Nvidia NVENC to create video streams in H.264/MPEG-4 AVC format, offering the best possible ratio between file size and quality.
GitHub releasenotes
Download the application on the platform you are interested in
Although the press releases will range from very select to rare, I said I'd pass...because sometimes the editors hide.

