Exchange Calendar API

Easy Exchange Calendar API integration with Cronofy

Data modeling and synchronization

Microsoft Exchange is the most popular option for businesses looking to host their employees' calendars and emails in-house. While this makes sense for them, it creates a nightmare for applications looking to integrate with that service.

What makes Microsoft Exchange truly unique – and even more difficult to integrate with – is that it sees everything as emails. Calendar events are emails with additional metadata, and calendars themselves are just email folders with this metadata attached.

This creates many vagaries when interacting with the Exchange Calendar API, and these are often at odds with how other calendar providers operate.

There are also subtle ways in which the many versions of Exchange differ, meaning you have to acquire and maintain significant amounts of knowledge to build a robust and reliable integration.

The Cronofy Calendar API encapsulates the learning from integrating with thousands of Exchange servers and processing millions of calendar events.

Microsoft-specific conventions

In the last decade, Microsoft has released 127 versions of Microsoft Exchange. That's 127 versions of Exchange that software must work with, and there'll be even more in the future.

The Exchange Calendar API also follows many Microsoft-specific conventions.

While these work well with Microsoft development and Windows environments, it makes it nearly impossible to interact with Exchange servers from open source, Unix environments.

Adding other popular calendar services such as Google Calendar into the mix makes integration even more of a headache.

Cronofy allows developers to create connections to Microsoft Exchange, Office 365,, iCloud, and Google Calendar while only developing for one API. This saves them time and helps to future proof any calendar integrations that they create.

Complex privacy concerns

Calendar integration using the Exchange API means resolving complex privacy challenges.

This is because developers are required to manage personal data in a safe, secure, and legal way for themselves and users that goes far beyond what the basic Exchange API offers.

Being in a default 'all or nothing' situation where data is concerned makes it impossible to control and comply.

Cronofy gives developers the option to create calendar integrations that only access users free/busy information. This protects users' privacy and offers developers greater flexibility in the software that they create.


An API for all sizes and budgets

You can use Cronofy if you’re working on a personal project with one user, if you’re part of an enterprise with a billion, or anything in between.

Data Modelling

Better data modelling

Calendar events are calendar events with Cronofy, not modified email messages as they are naturally with the Exchange API.


Simple & user-friendly

Cronofy works well with all calendar services and programming environments, not just Windows- and Microsoft-specific ones.


Support tailored for you

Have a question? Hit a brick wall? Want to show off what you’ve made? We’re here to help, listen, and admire whenever you need us.


Flawless synchronization

Dealing with calendar syncing can be a pain for both developers and end-users. Eliminate syncing issues permanently with Cronofy.

Active Development

On-going active development

Cronofy is always under active development – new updates are rolled out regularly. If you’re the early adopter type we also have an Alpha channel where you can be the first to try new features. On top of that, we offer a 99.95% uptime SLA as standard.


Considered, complete docs

We’ve carefully developed the Cronofy API documentation to ensure it contains everything you need in an easily accessible way. Forget about trawling through tons of separate incomparable docs for different calendar services – one set of Cronofy API docs covers all the major calendar providers.


Better privacy & security

Both businesses and end-users can rest assured that their data is safe, stored and transmitted in accordance with the law, and access is given on a need-to-know basis for everyone involved. Privacy and data protection are at the heart of what we do, and go far beyond the Exchange Calendar API’s natural security and privacy handling.

Derek Edwards

“The Cronofy API allowed us to add calendar sync support to our platform in a fraction of the time it would have taken to build support for separate protocols.”

— Derek Edwards, Co-founder & CTO, CoachLogix

Cronofy/Exchange Calendar API FAQs

Where do I get my Exchange Calendar API key?

Create a free Cronofy account and you’ll instantly have unified access to all the calendar services’ APIs, including Exchange Online. One key unlocks everything.

Do I need to be a Microsoft-registered developer to use the Exchange Calendar API with Cronofy?

No. You can use Cronofy and all its capabilities without having to be registered, accredited, or part of any program.

Do you have any sample apps or examples of Cronofy in use?

Check out our Sample Apps or have a look at our case studies to see what our customers have created so far and get inspiration for your own calendar integrations.

Is the Cronofy API limited to specific programming languages?

Nope – you can use any language you like. We have users coding in all kinds of languages.

However, if you’re using a common language like PHP or .NET, you may want to check out our handy code libraries for a head start.

How do I manage authentication using the Cronofy API?

We manage the authorization process automatically so you don’t need to do a thing.

You receive one Cronofy token for the user, which gives you access to all of their calendar services.

Can I use the Cronofy API to read Exchange calendar entries?

Yes. Cronofy gives you full access to Exchange calendar entries with user permission.

What are the API limits for Cronofy?

We don’t have a defined limit of requests, and we’re yet to see anyone come close to surpassing our current capabilities.

Which versions of the Microsoft Exchange API are supported by Cronofy?

The Cronofy API supports all available versions of the Exchange API and will continue to do so.

Can I directly replace my use of the Exchange Calendar API with Cronofy?


A single Cronofy API key also replaces the iCloud, Exchange,, and Office 365 calendar APIs. Use one of them, all of them, or a mix. It’s up to you.

I built something that uses the Cronofy API, what’s the best way to show you?

Definitely! You can tweet us @cronofy or email – we love seeing projects of all types!

What are the pricing plans for Cronofy?

If you’re only creating events, Cronofy is completely free of charge.

Our API is free for the first 20 users you have.

Beyond that, we offer affordable pricing plans.

How do I find out more about Cronofy?

You can find out more by emailing us at or by booking your Cronofy demo.

My question isn’t answered here, how can I get in touch?

Drop us an email at and we’ll be happy to answer any other questions you may have.

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