Updated 2026-09-25
ICS (.ics) is the file format almost every calendar app uses. Atrium speaks it in both directions.
Importing an .ics file
Import a file exported from Google Calendar, Apple Calendar, Outlook or another app. Its events are added to one of your own calendars and encrypted on your device like any other event.
Exporting
Export a calendar as an .ics file that other calendar apps can import. The export is decrypted on your device, so the file you save is readable; store it carefully.
Subscribing to a feed
Paste a calendar feed link (often ending in .ics, such as a school timetable or a sports fixture list) to subscribe. Atrium refreshes it regularly, hourly by default.
Subscribed calendars are not end-to-end encrypted. Our server has to fetch the feed from the internet to keep it up to date, so it can read what the feed contains. We store feed links and contents encrypted with our own key and never write feed links to our logs, but this is weaker than the protection on your own calendars. Don't subscribe to a private feed you wouldn't want us to be able to read.
Holiday calendars
Add public holidays for Canada or the United States, including provincial and state holidays. These work like subscriptions and have the same note about encryption.
Limits
The number of subscriptions (feeds plus holiday calendars) depends on your plan; see the pricing page.