Does the calendar *backend* matter? iCloud vs. Fastmail, etc

My calendar events have been stored in iCloud Calendars for as long as I can remember. I pay for iCloud (storage) and would continue to do so even without using their calendar service, but it would make more sense to me if I could consolidate my calendars into Fastmail since I’m using them for email.

This entire time I’ve been under the impression that Apple implemented some kind of proprietary calendar format. I was aware of something called “calDAV” but I just assumed Apple said “no thanks we’ll go our own way.” This is reinforced by things like the entire concept of “time to leave” because it doesn’t show up in the Fastmail website or in other apps like Outlook. So I just assumed that Apple Calendars stored extra bits of info in iCloud Calendars, which would not be compatible with other calendar services because those extra bits don’t exist.

Now that I have some more time and reading/playing around with it, it seems like I was wrong this entire time. Would there be any drawbacks in terms of missing features if I were to start using Fastmail exclusively to host my calendars, but using Calendars (iOS and macOS) as my frontend of the calendars? I would disable calendars in my iCloud account setup entirely. I have never used the invitation feature outside of work contexts, so losing the ability to invite other iCloud users to my events doesn’t matter to me at all. What’s important for me is that attachments, locations, reminders/alerts, and “time to leave” are all still available and work exactly the same way as they do now with iCloud.

Both iCloud and Fastmail use CalDav. I like hosting my cals where I host my e-mail for invites etc. It just seems to work better. For personal I host on Fastmail and for work Exchange. The MacOS and iOS stock Calendar app handles both without issue.

I do something similar with Google Calendar. I have no Apple Calendar-specific calendars but I have numerous GC ones which I subscribe to in Apple Calendar, and events changed in AC sync back to GC

I chose GC several years ago because I’d been having some issues with Apple Calendar, but I’ve come to love its power and features, like formatted notes and attachments to events, outstanding search, daily agenda email for selected calendars, add co-worker calendars and compare them side-by-side to note overlap and free time, calendar embedding for blogs, appointment slots and more.

Since this post I have moved all my calendars over to Fastmail. The move was simple enough—I just exported them on my Mac and dropped them into Fastmail.

I’m seeing two drawbacks:

  1. Syncing seems to be slow(er) now. I don’t remember how it was with the iCloud backend, but with the Fastmail backend I feel like I need to actually open the Calendar app on my iPhone and pull down to refresh for it to actually update. This means that my watch and the lock screen widget (on iOS) show me the wrong events until I manually refresh. If it happens in the background then it happens way too slow. I need to see if this same issue occurs with an iCloud calendar.

  2. The Fastmail backend does not give you the option to add file attachments to events. This is only available for the iCloud backend. This isn’t much of a problem but I liked being able to drop in a pdf of my boarding pass/tickets into the event so that I can access them from the event notification.

What happens if you use the Apple Calendar app and connect to the calendars on Fastmail server?

That’s what I’m doing. On both iOS and macOS I have Fastmail set up as a CalDAV server.

Also, the Calendars app on both iOS and macOS crash very often now, usually when I drag and drop events. Don’t remember this ever happening with iCloud.

All these problems are probably going to make me switch back.

In case it’s a Fastmail issue, they provide excellent support. Contact them.

Not sure about the crashing, but I think the delayed syncing is just an inherent problem of not having access to Apple’s APIs.

I just created a new iCloud calendar on my Mac and enabled it on my iPhone. New events added to this iCloud calendar on my Mac show up on my iPhone’s Calendar lock screen widget in near real time. If I move that event to a Fastmail calendar on my Mac, then the event just disappears from my iPhone’s lock screen widget even though other events in that calendar are still shown on the widget. Moving it back into iCloud on my Mac makes it show up again on my iPhone immediately.

Edit: It’s been over 10 minutes now and the lock screen widget still hasn’t updated properly with the new event in the Fastmail calendar.