OBS Studio is free and open source software for video recording and live streaming.
It is the re-write of the widely used Open Broadcaster Software, to allow even more features and multi-platform support. Currently Linux, Mac and Windows Builds are available.

• Official OBS Studio Builds: https://github.com/obsproject/obs-studio/releases
• Building OBS Studio Manually: Install Instructions

If you're looking for any kind of assistance with OBS Studio, the site has a help portal with links to resources and our support channels.

• OBS Studio Help Portal

The community has created a few guides on how to use OBS Studio:

• Quickstart Guide: OBS Studio Quickstart
• Overview Guide: OBS Studio Overview
• Guide to Sources in Studio: Sources Guide
• Guide to Filters in Studio: Filters Guide
• General Troubleshooting Guides: Troubleshooting Guides
• Volume meters guide (v21+): Understanding the Mixer
• Surround sound features: Surround Sound Streaming and Recording

For Support Questions, Discord, the forum and IRC are available:

• OBS Studio Discord
• OBS Studio Forum
• OBS Community Chat

More info about OBS Studio can be found in the Readme:

• ReadMe

Developers see the getting started tutorial, contributing guidelines, and copying info:

• Getting Started with OBS Studio Development
• Contributing
• Copying

For Development related Questions there is also a forum available:

• OBS General Development Forum