What are these Keybase URLs I see in many HN profiles?

Question

This is not guerilla marketing, I swear. I see these https://keybase.io public key URLs in many HN profiles. Of course, I checked out the website and I get the gist of it. But is it actually really popular? For active Keybase users, what do you use it for primarily?

toomuchtodo · Accepted Answer

Keybase: https://en.wikipedia.org/wiki/KeybaseAcquired by Zoom for their team's skills: https://blog.zoom.us/zoom-acquires-keybase-and-announces-goa... (2020)

denuoweb · Answer

I have one in my profile. It is just another encrypted chat and document sharing platform. You can verify yourself through the domain names you own or verify yourself through your hacker news profile, etc.