Tutorial: Adding Your First ICS Calendar Feed

What is an ICS feed?

ICS (iCalendar) is a standard format for sharing calendar data. An ICS feed is a URL that points to a live, read-only copy of a calendar. When you give manyCalendars that URL, it can pull in your events without needing to sync an open browser tab.

Think of Tab Sync as the quick, works-everywhere approach. ICS feeds are the set-it-and-forget-it approach. You configure the feed once, and manyCalendars refreshes it periodically in the background. No need to keep the calendar tab open.

Not every calendar supports ICS feeds. Some corporate tenants disable them for security reasons. But when they are available, they are worth setting up.

Finding your ICS URL

Google Calendar: Open Google Calendar in your browser. On the left sidebar, hover over the calendar you want and click the three-dot menu. Select "Settings and sharing." Scroll down to "Integrate calendar" and look for "Secret address in iCal format." Copy that URL. Important: use the secret address, not the public one, unless your calendar is set to public.

Outlook (personal): Go to Outlook on the web. Click the gear icon, then "View all Outlook settings." Navigate to Calendar, then Shared calendars. Under "Publish a calendar," select the calendar you want and choose "Can view all details." Click "Publish" and copy the ICS link.

Outlook (corporate/Microsoft 365): This depends on your organization's admin settings. Many corporate tenants disable ICS publishing. If you do not see the option under shared calendars, your IT admin has likely restricted it. In this case, Tab Sync is your best option.

Apple Calendar (iCloud): Open Calendar on your Mac, right-click the calendar in the sidebar, and select "Share Calendar." Check "Public Calendar" and copy the URL that appears. Note that iCloud ICS feeds can have longer refresh intervals.

Adding the feed to manyCalendars

Open manyCalendars and click the settings gear icon. Navigate to the "ICS Feeds" section and click "Add Feed." Paste your ICS URL into the field and give it a name (something like "Client A - Google" so you remember which calendar it represents).

Click "Save." manyCalendars will fetch the feed immediately and add the events to your unified view. You should see the new calendar appear in your sidebar with its own color assignment.

Repeat for each calendar that has an ICS feed available. You can mix ICS feeds and tab-synced calendars freely. manyCalendars treats them the same way in the unified view.

What to expect

Sync timing: manyCalendars checks ICS feeds periodically while the extension is active. The default refresh interval is configurable in settings. Keep in mind that the calendar provider also controls how quickly changes appear in the ICS feed itself. Google Calendar feeds typically update within a few minutes. Outlook and iCloud feeds can take longer.

Read-only: ICS feeds are one-way. manyCalendars can read events from them but cannot write back to the source calendar. You cannot create or modify events through an ICS feed. For that, use the source calendar directly.

Limitations: Some ICS feeds only include events within a certain time window (often 30 to 90 days in the past and future). Very old or very far-future events might not appear. Additionally, if your organization disables ICS feeds, no amount of configuration will make them work. Tab Sync is the fallback for those calendars.

ICS feeds and Tab Sync cover different situations. Use feeds for calendars that support them and tabs for everything else. Between the two, manyCalendars can get every calendar you touch into one view, regardless of which vendor or tenant it lives in. That is the whole job.