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Use cases → Scheduling

Check multiple users’ calendar availability at once

Query many users’ free/busy calendars with a delegated service account to coordinate group scheduling without asking each person individually.

Who it is forAnyone building a scheduling tool or workflow that needs to find a common available slot across several users.
APIsCalendar API
Typical scopescalendar.readonly

The problem

Manually checking each attendee’s calendar is slow and error-prone, especially across teams or departments. Automating the process avoids missed slots and endless back-and-forth, but requires careful handling of access and batching.

How it works

  1. Impersonate each user via domain-wide delegation with the service account.
  2. Use the Calendar API’s freeBusy.query endpoint to request availability for all relevant users in one call.
  3. Parse the response for overlapping free slots.
  4. Propose or automatically book a meeting in an available window, if desired.

What changes

Group availability is surfaced in seconds, making large-scale scheduling practical and reducing manual coordination.

The trap in this one. The Calendar API’s freeBusy.query endpoint will silently omit users whose primary calendars are not provisioned or are disabled, returning no error and an incomplete picture. If you do not explicitly check that all requested users are present in the response, you risk proposing slots where some attendees are actually unavailable. This is easy to miss in production, especially when onboarding new users or handling suspended accounts.

Watch it explained

“google calendar API” — nghia doan on YouTube. Third-party video, included because it covers this ground well. We are not affiliated with the channel.

Questions people ask

Does this work for external guests?

No, only users within the Workspace domain that the service account is delegated to can be impersonated for free/busy queries. External calendars will not be included.

What calendar is checked for each user?

Only the user’s primary calendar is queried by default. Secondary calendars and shared calendars are excluded unless explicitly specified.

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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