Born from years of calendar sync pain.
Apisaurus is the unified calendar API built by the team behind OneCal, so you never have to wrestle with calendar provider quirks again.
Why we built Apisaurus
We built OneCal, a calendar synchronization product used by thousands of people to keep their calendars in sync across Google Calendar, Outlook, and iCloud Calendar. Over three years, we processed hundreds of millions of events and ironed out every edge case imaginable: timezone quirks, recurring event modifications, OAuth token refresh flows, and provider-specific data models.
We kept hearing the same thing from developer teams: "We wish we could just use one API for all calendar providers." They were spending months rebuilding what we had already solved. So we built Apisaurus, a single, unified API that works the same way across every provider.
Proven at scale
- Events synced
- 500M
- Syncs executed
- 20M
- API success rate
- 99.0.9%
- Years of calendar expertise
- 1+
Why it matters
We know the pain of calendar APIs.
Every lesson we learned building OneCal is baked into Apisaurus, so you can skip the months of trial and error.
One API, every provider
Google Calendar, Outlook, and iCloud through a single, consistent interface. No more provider-specific code paths or data transformations.
Battle-tested reliability
Built to scale, the Apisaurus Unified Calendar API has processed billions of requests and continues to handle millions daily with high reliability.
Ship in hours, not months
Full CRUD operations, real-time webhooks, and recurring event support out of the box. Spend your time building features that matter to your users.