Remotely Open Source
https://remotely.one/
https://github.com/immense/Remotely

How It Works

The Remotely client has two parts: the service and the remote control. The service is responsible for maintaining a persistent connection to the server and executing remote commands. The remote control is launched as needed for remote control sessions.

Both applications make outgoing websocket connections over secure SSL/TLS protocol. Because the connections are outgoing, you don't need to open any ports in your firewall, and the service won't accept any incoming connections.

The Remotely service will register with your Remotely organization ID, which is generated when you create your account or join an existing organization. On the first connection, the service generates a separate unique ID and sends it to the server. Upon each subsequent connection, the server must send back that ID before anything else, or else the service will uninstall itself immediately. This is an additional layer of security that ensures the service is communicating with the original server.

Users and computers are grouped into an organization, and they can't interact with resources outside their organization. Microsoft's Identity framework is used for all login and authentication to verify users.

Notable Features
• Support for Windows and Linux devices
• Unattended and attended access
• Remote scripting for Windows PowerShell, PowerShell Core, Bash, and CMD
• Optional WebRTC for secure peer-to-peer screen transfer on Windows agents, which reduces load on the server
• Drag-and-drop file transfer
• Remote audio streaming (Windows only)
• Bi-directional clipboard sharing
• Custom branding for desktop apps
• Integrated chat
• Scheduled scripts
• Device alerts
• 2-factor authentication

Does not work on MAC.