iCloud Calendar API, Simplified

Integrate with Apple Calendars without using CalDAV

How to be an effective developer at a startup

“We were looking at writing custom integrations for a few calendar services, but by using Cronofy we were able to connect to several in far less time.”

— Greg Woods, Lead Developer, Iris Works

Connecting schedules

There are millions of iPhone users out there.

Allowing them to connect their Apple Calendar to your application creates a better user experience and puts you one step ahead of your competition.

However, it's not easy.

The only way to connect to iCloud is using CalDAV. This client/server document protocol is used to submit and retrieve Apple Calendar documents.

Unfortunately, CalDAV can be a challenge for developers used to more commonly styled HTTP APIs.

This mean that many applications that could benefit from calendar sync don’t take advantage of it and their users miss out.

Using Cronofy's unified calendar API, you can solve these problems and more.

Calendar sync for iPhone, iPad, and Mac.


With traditional calendar integration, two versions of an event exist in two different calendar services.

Both can be updated independently, meaning that if an event is cancelled or rescheduled, one party may miss out on important details.

To avoid conflict deadlocks and infinite update loops, you’re responsible for handling ownership and state transitions.

The Cronofy API resolves these synchronization challenges.

Changes to calendar events are idempotent. You don't have to worry about if an event already exists or not, you just tell us what state you want to it be in and we'll make the necessary changes.

Cronofy also differentiates between events sourced from your application (‘Managed’) and events already in the user’s calendars (‘Unmanaged’) to ensure that you have reliable integration from the start.

Bring calendar sync to your customers


Only allowing users to connect to one calendar service can result in a poor user experience.

It could even mean that they don't use your product and go to a competitor instead.

Connecting software to multiple calendar services, however, is a costly investment.

You have to spend time not only creating individual connections to each calendar API, but also maintaining those connections and ensuring it works with previous versions of each calendar service.

When you use Cronofy, you can code for just one API and connect your software to iCloud, Google Calendar, Office 365, Outlook.com, and Exchange.

All the maintenance is handled by us, meaning that you have more time to spend on creating a great product for your customers.

Calendar sync for Apple Calendar.


The iCloud Calendar API offers limited connectivity options.

Either your application can access everything in a user's calendar, or nothing. There is no other option.

Unless you use Cronofy.

With Cronofy, you can customize how much of a user's calendar your software has access to.

If it only needs their free/busy data, you can set it up so that that's all it will see.

This free/busy data can be hosted on our EU or US servers.

Add calendar sync to your Mac OS and iOS apps.

Try Our API

Sync your software to iCloud, Google Calendar, Office 365, Outlook.com and even Microsoft Exchange

Cronofy also offers...



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.

James Balmain

“The documentation and support provided by Cronofy is first rate. It meant our engineering team were able to rapidly integrate calendar sync functionality into the Zesty platform and deliver value extremely quickly. The almost non-existent maintenance overhead means we'll continue to accrue value from this work for a long time to come.”

— James Balmain, CEO, Zesty

Cronofy/iCloud Calendar API FAQs

How do I use the Apple iCloud Calendar API via Cronofy?
Sign up and take a look at our API documentation.

Use our docs instead of the iCloud API docs and connect your calendar in a click from your Cronofy account dashboard.

What pricing options are available for Cronofy?
Cronofy is free for the first twenty users or if you’re only creating events. For more details, visit our pricing page.

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 the 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 which enables 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?

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?
Yes! Take a look at our Sample Apps.

Should I be an Apple-registered developer to use the iCloud Calendar API with Cronofy?
No – 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! Email us at hello@cronofy.com 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.

Powering clients...

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