Easy RSVP is a homemade solution to the one thing I miss from Facebook: events. It lets you publish an event and makes it super quick and easy for your guests to RSVP. No account required, no email, no password.
It also served as an excuse to do some practical research on authentication-less product design. In light of GDPR, adtech abuse and regular data leaks, I've grown curious about account-less apps or authentication-less features. How useful can you make a web app without requiring any personal information, name, email or password?
Oh, and it's open-source.