EVOTECH digital · custom software · APIs & Integrations

Calendar API Integration

Two-way sync with Google Calendar and Outlook so your app can create events, read availability, and stay in step when users change things on their side.

5.0· 14 Google reviews

Real scheduling features, not a fragile hack

Whether you're building booking, dispatch, resource scheduling, or reminders, the hard part isn't creating one event — it's keeping your app and the user's real calendar agreeing after edits, cancellations, and reschedules happen on either side.

We build against the Google Calendar API and Microsoft Graph so events flow both ways and your app reflects what the user actually sees in their calendar.

  • Create, update, and cancel events from your app into the user's calendar
  • Free/busy and availability lookups to power booking and conflict checks
  • Push notifications (Google) and change subscriptions (Graph) for live updates
  • Recurring-event and exception handling done properly, not approximated
  • Time-zone-correct handling so 9 a.m. means 9 a.m. for everyone involved

The details that break naive calendar sync

Calendars are deceptively messy: recurring meetings with one-off changes, all-day vs. timed events, daylight-saving shifts, and multiple calendars per account. Skipping these is what makes a sync 'mostly work' until it embarrasses you.

We handle the edge cases up front and add reconnection handling for when a user revokes access or changes their password, so the connection recovers cleanly.

  • Correct treatment of recurring series, single-instance overrides, and deletions
  • Daylight-saving and cross-time-zone correctness
  • Duplicate-prevention so a sync retry doesn't create ghost events
  • OAuth token refresh and clean re-consent when access is lost
  • Support for users with multiple calendars under one account

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Frequently asked questions

Can it sync both Google Calendar and Outlook for the same app?

Yes. They use different APIs — Google Calendar API and Microsoft Graph — so it's two integrations under one feature, but users can connect whichever they use. We build a common layer in your app so the rest of your code doesn't care which provider is behind a given user.

What happens if a user edits an event directly in their calendar?

With a true two-way sync and change notifications, your app hears about it and updates its own record. We set up the subscription/push mechanism each provider offers so you're not polling constantly and not missing changes.

Do you handle recurring meetings correctly?

Yes, and it's worth asking because many quick integrations don't. Recurring series with a single moved or deleted instance are a common source of bugs. We handle the series, its exceptions, and cancellations explicitly.

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