I'd probably start with google calendar's docs.

Looks like it has a decent API for this: https://developers.google.com/calendar/api/guides/recurringe...

Edit: also this: https://developers.google.com/calendar/api/v3/reference/even...

The first link looks like a good translation of the iCalendar to JSON, I guess you can't really beat the iCalendar standard when it comes to representing events!

I would use "recurrence rules", but curious to hear more.

https://icalendar.org/iCalendar-RFC-5545/3-8-5-3-recurrence-...

https://jakubroztocil.github.io/rrule/

https://github.com/jakubroztocil/rrule

All best with your project

Those libraries are helpful thanks! I didn't know icalendar had an RFC, very helpful!

Many years ago, I built a calendaring system and I ended up implementing iCalendar but in a database instead of a file. I would not recommend doing it the way I did, but I did come to the conclusion that if you want to support the same types of recurrences, you really should be very familiar with how icalendar handles things or you'll forget something important.