I'm doing a new Show HN[1] as we have now made this open source, and got some interest in comments in the past few days.<p>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.<p>First I suggested a shared Google Sheets or Calendar, but that was also messy to maintain.<p>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.<p>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.<p>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...).<p>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).<p>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.<p>[1]: <a href="https://news.ycombinator.com/item?id=42510407">https://news.ycombinator.com/item?id=42510407</a>