Office 365 Calendar API

Office 365 Calendar REST API Office 365 is Microsoft's cloud version of its business suite of software. What was an Exchange server that was run locally is now available as a maintenance-free cloud service.

One of the key challenges with integrating with Office 365 is the incompleteness of the API. Features available in other calendar APIs - such as reminders - are nowhere to be seen, making it even more of a challenge to work with multiple calendar API providers. Furthermore, the Office 365 API, just like all the other major calendar APIs, also has significant shortcomings when it comes to protecting data as it works from an 'all or nothing' perspective.

Overcoming these challenges requires continual investment in time and resources, with plenty of development headaches along the way. That’s why we created Cronofy.

What is Cronofy?

Cronofy is an API for easy, seamless calendar integrations across all services. Instead of dealing with individual calendar APIs that were never designed to play well together or provide optimum synchronicity or privacy, use Cronofy to make developing with calendars a breeze. All you need is one free account and our getting started guide for complete calendar integration for Office 365, Google Calendar, iCloud, and more.

Take advantage of unlimited events, and create systems without worrying about user restrictions or per-event charges. It’s just as easy to use five calendar services as one, meaning that your users can enjoy a complete, reliable scheduling service without changing their workflow. Best of all, there’s no hassle or extra work involved for you. Cronofy is able to use the Exchange APIs to interact with the Office 365 infrastructure and this deliver feature parity with on-premise Exchange.

Cronofy is calendar integration made simple, with one unified API for all services.

Office 365 Calendar API with Cronofy

Jez Louise

Cronofy enables our clients to seamlessly add tasks to their calendars, improving efficiencies and avoiding any double-handling. Our internal support team also gets just as much value out of it as our clients!

— Jez Louise, Support Manager, JobAdder

With Cronofy you get all the standard features of the Office 365 Calendar API plus…


Global environment compatibility

Cronofy has been built for easy integrations across all programming languages, frameworks and environments, not just those specific to Microsoft and Windows.

Calendar Compatibility

Unified calendar access

Cronofy not only provides you with the Office 365 Calendar API, but also the calendar APIs for, Exchange, Exchange, iCloud and Google Calendar…all in one place.


Better user experience

Cronofy ensures easier development and better UX out of the box. Offer your users integration with the calendar service of their choice without extra work on your part.

Active Development

Guaranteed active development

Our calendar API benefits from new releases and changes rolled out on a regular basis. If you’re the early adopter type, we also have a separate Alpha channel for you to test upcoming features.


Calendars everyone can rely on

We’ve resolved the standard synchronization problems so common with calendar development work so that you and your users can rely on precise availability and up-to-the-minute booking information.


Practical API documentation

The Cronofy API docs are all you need to get full access to five different calendar APIs. Crafted by our own in-house developers, our API documentation is a concise resource that contains everything you need for robust calendar integration.

High Uptime

99.95% uptime SLA

We guarantee a minimum uptime of 99.95% so you can rest assured that you’re offering users a highly dependable service 24/7.

Data Modelling

Data modeling

Privacy is one of our biggest priorities. Data is handled securely and as a developer you only access required information, unlike the standard Office 365 API.


Dedicated support

Our team is on hand to help with any questions you have about Cronofy, integrations, documentation, and so on.

Connect the world's calendars

Smarter, faster, safer integration with docs, tutorials, and full support.

Frequently asked questions

How do I use the Office 365 Calendar API through Cronofy?

Everything is handled via your developer dashboard, so simply create a free Cronofy account and then take a look at our tutorials for further guidance.

Do I have to be a Microsoft accredited developer to use the API?

Anyone can use the Office 365 Calendar API through Cronofy; you don’t need Microsoft accreditation or certification.

Can I use Cronofy instead of the Office 365 Calendar API?

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

Do you have examples of Cronofy in use in the wild?

The Cronofy API plays a backend role in the wild, so we’ve added Sample Apps and Use Cases to our site so you can get a better idea of what you can do and how it works.

What are Cronofy’s pricing options?

We’ve designed Cronofy to make it affordable for everyone, regardless of whether you’re working on a hobby project or integrating calendars for millions of users. If you’re just creating events or you have fewer than twenty users, our API is free. After that, it’s a low, flat fee without charges for API transactions or events. See our pricing page for more details.

What are the limits on the Cronofy API?

Cronofy isn’t restricted to any specific languages, frameworks or environments, so you’re free to use anything from C# to PHP. If you’re still deciding, it’s worth checking out our code libraries.

How does authentication work?

Authentication is handled automatically by Cronofy, which means one less development job to worry about.

What kind of support do you provide for the Cronofy API?

Just drop us an email at and our friendly developer team will help you out with any questions or problems. We also have API docs, tutorials, code libraries and sample apps.

I have another question and/or would like to book a chat. How can I contact you?

Drop us a line at or fill out the form below and we’ll be in touch!

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