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Use cases → Scheduling

Auto-update public holiday calendars across all users

Push new or revised public holiday events into every user’s calendar, without manual imports or missed recipients.

Who it is forIT or HR teams maintaining consistent holiday schedules across a domain.
APIsCalendar API
Typical scopescalendar

The problem

Manually importing or sharing public holiday calendars leads to inconsistent coverage—users miss updates, duplicates creep in, and new starters get out-of-date lists. Automating this with a service account gives full coverage but requires careful event management.

How it works

  1. Maintain a canonical holiday event list in a central source (spreadsheet or database).
  2. Enumerate all active user calendars via the Admin SDK.
  3. For each user, upsert (insert or update) each holiday event using a consistent eventId.
  4. Remove any obsolete holiday events based on the canonical list.
  5. Log all changes for audit and troubleshooting.

What changes

Every user’s calendar reflects the current official holiday list, with changes propagating automatically and old entries cleaned up.

The trap in this one. If you generate a new random eventId for each upsert, users accumulate duplicates every year—Calendar API treats eventId as the deduplication key. Worse, if you re-use predictable eventIds but change the event’s time or description, mobile clients sometimes fail to sync the update, showing stale data until a full resync. Always test updates across multiple clients, and consider forcing a sync by bumping the iCalUID if you must override an event.

Watch it explained

“Mastering Google Apps Script: Holiday Calendar Automation in Google Sheets” — Aris Azhar on YouTube. Third-party video, included because it covers this ground well. We are not affiliated with the channel.

Questions people ask

Why not just share a single read-only holiday calendar?

Shared calendars are easy to miss, and users can hide or unsubscribe from them. Injecting events ensures visibility and mobile reminders, but at the cost of more careful event management.

Can this run as a batch job?

Yes, but watch for Calendar API write quotas and back off if you hit 429s. Staggering updates or running nightly reduces user impact.

Want this built?

This is a pattern we run in production. We will set up the delegation and build this on top of it — $500 per hour, most of it working the same day.

Talk to us Or read the setup guide

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