OBS Studio

OBS Studio (formerly known as Open Broadcaster Software: Multiplatform) is free and open source live streaming and video recording software.

Features:

Multiplatform support

OBS Studio developed with cross-platform support. Official releases are currently available for Windows, Mac and Ubuntu Linux. There are also some unofficial releases for Arch Linux, OpenSUSE and Gentoo. And of course, since source code is open, you can build OBS for your OS.

You can contribute to OBS Studio

While OBS Studio is free and open source, you can suggest your code to official repository. Here are some guidelines for contributors.

Also, it has powerful API, enabling plugin development to provide further customization and functionality specific to your needs.