Covalence
Chat, calls and screen sharing with your friends, straight between your computers. Free.
Windows says it “protected your PC”?
The installer isn’t signed with a paid certificate yet, so Windows doesn’t know it. Click More info, then Run anyway. Once it is in, the app keeps itself up to date: every update is signed by the people who make it, and checked before it is used.
What it is and how it works: covalence.chat