https://arstechnica.com/gadgets/2019/12/nebula-vpn-routes-between-hosts-privately-flexibly-and-efficiently/

Last month, the engineering department at Slack—an instant messaging platform commonly used for community and small business organization—released a new distributed VPN mesh tool called Nebula.

It's difficult to coherently explain Nebula in a nutshell. According to the people on Slack's engineering team, they asked themselves "what is the easiest way to securely connect tens of thousands of computers, hosted at multiple cloud service providers in dozens of locations around the globe?" And (developing) Nebula was the best answer they had. It's a portable, scalable overlay networking tool that runs on most major platforms, including Linux, MacOS, and Windows, with some mobile device support planned for the near future.