LastSeen is intended to be a super minimal socially thing.
Probably anti-social, but whatever.
The idea is simple: you install/use some program/software on your device/computer and when used it will
ping our server to update your last seen time. Your custom https://lastseen.me/page ends up something like what you can see here
When you register you'll choose your custom url and can then post it wherever you'd like.