Aurinko Calendar API vs Google Calendar API

Aurinko Calendar API

A public OpenAPI 3.0 spec covers 154 operations, with free/busy, meeting-time suggestion and booking profiles alongside calendar reads and writes, and prices start at $1 an active account a month. No status page, SLA, changelog or official SDK was found, and the application's client secret reaches every connected account.

Google Calendar API

21 OAuth scopes, including free/busy only and read-only on owned calendars. Google calendars only.

Aurinko Calendar API

1. Use https://api.aurinko.io/v1. Several cURL examples in the docs print https:/api.aurinko.io with one slash
2. Send If-Match with the event's etag on PATCH /v1/calendars/{calendarId}/events/{eventId}. A stale value returns 412
3. Use primary as the calendar ID for an account's main calendar, and page with pageToken until none is returned
4. Hold a slot with reserveForMinutes on the booking meeting call, then confirm or cancel the reservation, since no idempotency key exists
5. Retry 429, 408 and 5xx with exponential backoff. Do not retry 404. A 429 can come from Google or Microsoft limits behind the API

Google Calendar API

1. Ask for calendar.events.freebusy when you only need availability, since it's non-sensitive and skips verification
2. Set your own event id on insert, and treat a 409 as already created
3. Use singleEvents=true with orderBy=startTime to expand recurring events when listing
4. On 410 fullSyncRequired, drop the stored syncToken and do a full sync
5. Back off exponentially on 403 and 429 usageLimits, up to 32 or 64 seconds