api – Free/Busy Calendar Cloud Service


Project

I’m currently developing an app for a client, where you can look for services (plumber, driving lessons, bike repair, …) in your vicinity and book from the app.

Now my client wants to add a feature, that any registered service provider can supply a free/busy calendar so that bookings don’t overlap.

The project is using Contentful CMS as backend (fully cloud-hosted), so I don’t have a managed/dedicated server.

What I need:

A 3rd party free/busy calendar provider, where:

  • Service providers can sign up (easily) and create their own personal calendars
  • I can query a service provider’s calendar from the app
  • Add an appointment programmatically once it has been booked
  • Potentially show a widget of the calendar in the app

What I tried

Most intuitive choice would be Google Calendar, but to allow write access the service provider would have to go through some pretty complicated steps to enable Google API from what I’ve seen, so this does not seem like a viable option.

Contentful CMS does not appear to have any suitable add-ons or extensions.

Does anybody know of a cloud service that would be suitable for this task?