Import Busy Times from Any Other Calendar

Zimun can read the busy times from almost any calendar that publishes an iCal (ICS) address — Nextcloud, Fastmail, Proton Calendar, a self-hosted server, and others. You paste the address once; Zimun refreshes it every 15 minutes and imports only the times of your events — never titles, descriptions, or attendees. From then on, an outside appointment closes the overlapping Zimun slots the same way a Zimun appointment would. Customers simply see fewer available slots; nobody sees why.

This covers one direction: outside events blocking Zimun. For the other direction — seeing your Zimun appointments inside your calendar app — subscribe to your Zimun calendar feed from Settings → Calendar feed. The two links together give you two-way visibility without connecting any accounts.

1. Find your calendar's ICS address

The exact wording differs per app, but the feature is usually in the calendar's sharing or export settings, under a name like:

• "Subscription link"
• "iCal link" or "ICS link"
• "Export calendar URL"

1. Open your calendar app's settings for the specific calendar you want Zimun to read.
2. Look in the sharing or export section for one of the names above.
3. Copy the address. It may start with https:// or with webcal:// — Zimun accepts both; paste a webcal:// address as-is.

Two things to check while you are there:

• You need an address, not a file. Some apps also offer a one-time .ics download — that is a snapshot of your calendar, and Zimun cannot refresh it. Copy the link, not the download.
• If the app offers several link formats and you are not sure which one is the feed, just try one: the validation check in the next step tells you whether it worked.

2. Paste the address into Zimun — and let the check tell you

1. In Zimun, open Settings → Team and open your own record. The External calendar tab appears only on your own record — nobody can paste an address on your behalf, and you cannot paste one for a teammate.
2. On the External calendar tab, paste the address into the calendar address field and save.
3. Zimun fetches the feed once, right away, and answers with "Events found in the next 14 days: N."

With a provider not covered by the other guides, this check is your ground truth. If you see the events-found message, the address is a working calendar feed and you are done. The number counts events in the 14-day window Zimun watches — a count of 0 is not an error if your next two weeks happen to be empty. If the check fails instead, the message states the problem and nothing is saved: go back to your calendar app and look for a different link (a page link or a download link will not pass), then try again.

Once connected, the tab shows the address masked, a "Last refreshed" timestamp, and a Remove button. Remove stops the import and deletes every busy block the feed created.

3. How fresh the import is

Zimun refreshes the feed every 15 minutes; "Last refreshed" on the External calendar tab shows the most recent run. How quickly your provider updates the published feed after you change your calendar is up to the provider — some serve current data, others regenerate the file on a delay. If a fresh event takes longer than 15 minutes to block your Zimun slots, the wait is on the provider's side.

4. Keep the address private

The ICS address of your calendar grants full read access to that calendar to anyone who holds it — treat it like a password. Zimun stores the address encrypted, shows it only in masked form, and keeps only busy times from your calendar: the start and end of busy slots, never titles, descriptions, or attendees. Event contents pass through Zimun's server only transiently during each refresh and are never stored. Removing the feed deletes the address and every imported busy slot.

Connecting a calendar is always each member's own voluntary step: whether and how an organization asks its staff to do so — including any works-council involvement or other employment-law obligations — is the organization's responsibility as employer, not Zimun's.

Do not post the address, and do not send it to anyone you would not hand your calendar to. If you think the address has leaked, revoke or regenerate the link in your calendar app's sharing settings so the old address stops working, then paste the new one into Zimun.

5. Troubleshooting

• The External calendar tab shows a needs-attention state: the feed has stopped answering. The usual cause is that the link was revoked or regenerated in your calendar app. Get the current address (section 1) and paste it into Zimun again. The state appears only after a couple of hours of failed refresh attempts, so a single network hiccup will not trigger it.
• An event is not blocking your slots: events marked free are skipped on purpose — only busy time blocks availability. Also check the horizon: Zimun watches the next 14 days, so events further out start blocking as they roll into that window.
• Slots disappeared unexpectedly: that is the feature working. All-day events block the whole day, and tentative events count as busy. Move or delete the event in your calendar, or remove the feed in Zimun to stop the import entirely.
• The validation check keeps failing on every link you try: your app may not publish a subscribable ICS feed at all, or only for calendars you own rather than ones shared with you. Check the app documentation for "iCal subscription" or "calendar export URL".