iCloud Calendar API

Apple iCloud Calendar API Every single one of the hundred of millions of iPhone users out there is actively encouraged to have an iCloud account by the Apple on-boarding process. Access to the iCloud calendar that is then enabled on their iPhones relies on both an understanding of CalDAV as well as how Apple handles authentication.

The only API into Apple Calendar is CalDAV. This is a client/server document protocol that is used to submit and retrieve iCalendar documents. CalDAV can be a challenge for developers used to more commonly styled HTTP APIs.

With the number of Apple devices growing rapidly year on year, making apps and other software integrate with iCloud is increasingly important. However, working with Apple’s Calendar API is a challenge due to:

Synchronization problems

With calendar integration, you have two representations of an event existing in two application domains, both of which can be updated independently.

To avoid conflit deadlocks and infinite update loops, you’re responsible for handling ownership and state transitions; this isn’t naturally accounted for by the iCloud API.

Unlike the Google Calendar API, the Cronofy API is built to resolve these synchronization challenges. Events upserts and deletes are idempotent. We also differentiate between events sourced from your application (‘Managed’) and events already in the user’s calendars (‘Unmanaged’) to ensure you have a reliable integration out of the box.

Legal & privacy challenges

The iCloud API has an all-or-nothing approach to data access (i.e. you can read everything or nothing).

If you want to provide rich calendar integration using Apple’s API, you have the complex challenges of managing personal data in a safe, secure way for both yourself and end-users.

Multi-provider limitations

Calendars are notorious for challenging integrations, and working with multiple APIs such as Google Calendar, Exchange, and iCloud is a stressful and time-consuming experience.

On the flip side, only integrating with one service means forcing user behaviour and applying concrete limitations. There has to be a compromise somewhere, and it’s either the developer or end user who suffers.

Happily, you can resolve all these problems in one step by using Cronofy.

What is Cronofy?

Cronofy is a fully managed unified API that works seamlessly across all calendar services. With Cronofy, you remove all the downsides to integrating using the iCloud calendar API but still take advantage of all the benefits.


We manage all the calendar APIs, handle privacy, and make integration easy so you don’t have to waste your time trying to make everything play nicely. It’s just as easy to use five calendar APIs as it is one, and there’s no limit on the number of users or events you can have.

Apple Calendar API - Cronofy

The Cronofy API has been developed around resolving the challenge of calendar synchronization. Events upserts and deletes are idempotent. Furthermore, events sourced from your app and events already in the user’s calendars are treated as separate ‘Managed’ and ‘Unmanaged’ events respectively. The result is effortless synchronization built in from the start. Our permissions enable you to interact with calendars without reading any data you don’t need. Not only are you delivering a great experience to your users, you’re giving them confidence that their privacy is protected at all times.

Make calendar integration easy

One set of docs, one API, no hassle.

In addition to all the features of the iCloud calendar API, Cronofy gives you:


All calendar APIs

Integrate with the iCloud, Outlook.com, Office 365, Exchange, and Google Calendar APIs via Cronofy for universal calendar functionality minus the hassle.



Avoid dealing with frustrating CalDAV/Apple Calendar API integration and spend your time on interesting parts of web development - Cronofy does the boring stuff for you.


Full documentation

A single concise set of Cronofy documentation is all you need for all the calendar APIs. We’ve carefully developed our API documentation for clarity and ease of use.



Enjoy peace of mind with our standard 99.95% uptime SLA.



One user or one billion, Cronofy scales for your needs.

Active Development

Active development

We release new features and updates regularly.


Fast syncing

Cronofy's advanced approach to synchronization means your users always have calendars they can rely on.


Better privacy

We handle privacy more effectively for both businesses and end-users, and we’re always on hand to help.


A voice

We have a public platform for ideas and feedback, and actively implement user suggestions.

Make the world's calendars better

Register for your Cronofy Developer account - it's free!

Leah Hutcheon

The integration itself was a straightforward project and the lines of communication were open between our two development teams. We would recommend an API integration with Cronofy to anyone looking to hook external calendar functionality to their app.

— Leah Hutcheon, Founder & CEO, Appointedd

Frequently asked questions

How do I use the Apple iCloud Calendar API via Cronofy?

Sign up and take a look at our API documentation. Simply use our docs instead of the iCloud API docs and connect your calendar in a click from your Cronofy account dashboard.

Where do I get my Cronofy iCloud Calendar API key?

A single Cronofy API key gives you access to all the major calendar services’ APIs, including iCloud. To get your universal key, create a free Cronofy account.

What pricing options are available for Cronofy?

Cronofy is free for the first twenty users or if you’re only creating events. After that, it's a low flat cost without any crazy API transaction or per-event fees. See our pricing page for more details.

Have you got a Cronofy iCloud API tutorial?

We’ve created a ten-minute quick start guide: Getting started with the Cronofy Calendar API. It’s a succinct tutorial that will take you through setup and getting started processes.

Can I show you something I made with the Cronofy API?

We love seeing and sharing projects that use the Cronofy API – no matter how big or small. Tweet us @cronofy or email hello@cronofy.com.

Which languages does Cronofy support?

You can code in any language you like when working with the Cronofy API. It’s completely flexible and we have users spread across a wide variety of languages.

How does authentication work for Cronofy and the iCloud API?

You receive a single Cronofy token for each user, enabling you to access all their calendar services (including iCloud). We manage the authentication on your behalf to make it simple and secure.

Can I use Cronofy as a straight replacement for the Apple iCloud Calendar API?

Yes, you can use Cronofy instead of any or all of the following calendar APIs: iCloud, Exchange, Office 365, Outlook.com and Google Calendar.

Do you have any integration examples/samples that use Cronofy?

Take a look at our Sample Apps to see how Cronofy works in practice.

Should I be an Apple-registered developer to use the iCloud Calendar API with Cronofy?

Nope, you can use it regardless of whether you’re a registered Apple Developer or not.

Is there someone I can talk to about Cronofy/calendar integration?

Sure, just send us an email at hello@cronofy.com or fill out the form below and we’ll work out a time and format that suits you.

I have a question that isn’t answered here – how do I contact you?

Send us an email at support@cronofy.com and we’ll get back to you as soon as possible.

Find out more

We'd love to learn more about your business and explore how we could help. Fill in your details and one of our team will be in touch.

“Our new calendar sync functionality has made me super giddy! It's so easy to authorize and get up and running!”

— Leah Hutcheon, CEO, Appointedd

Begin integrating calendars - it's free

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