We initially built this app for some friends in a co-living community - they were using pen and paper to track who's attending lunch - but it was error-prone.
First I suggested a shared Google Sheets or Calendar, but that was also messy to maintain.
Eventually, I developed something just for them. They used it for a couple of years, they loved it and wanted to use it for more things, too.
So I took all the learnings from what was now the MVP, and with some friends we now launched this new version, built on Flutter and Supabase.
Supabase was to give us some better control on the data; dealing with events and especially recurring events gets really messy really quickly. The data model on Firebase was horrible (so much duplications...).
And Flutter to quickly offer good mobile apps for everyone, since a feedback I often got before was that the "PWA" didn't really feel like a real app at times (especially on iOS).
We decided to make it open source as there'd be many possibilities to extend it, from making it more compatible with business features (say a CalDAV integration); to allowing more "rich" events and anonymous access to compete with Apple Invites or Partiful; to introducing some discovery and ticketing features and compete with Meetup or Eventbrite.