Open Broadcaster Software is free and open source software for recording and live streaming. Source code is available to everyone to contribute and improve. Both 32 and 64 bit versions are available and it's absolutely free!
Free! Not a dime! There are no subscriptions or anything, no payments at all. OBS is available to everyone, with all features, at absolutely no cost!
OBS has an API allowing developers to create their own unique plugins, giving them and others complete control of their streaming experience.