Outlook.com Calendar API

Outlook Calendar APIOutlook.com is the latest in a series of rebrands of Microsoft's consumer email and personal organisation platform. What was Hotmail became Live and now, confusingly, uses the same name as their famous email client software.

Outlook has its own set of APIs so is yet another fragmentation of the calendaring services. As an added bonus, the Outlook.com API also has more feature limitations that need to be worked around. Utilising the Outlook.com Calendar API means undertaking a series of privacy challenges to ensure that you’re storing and processing data safely and legally for users and yourself as the API doesn’t handle this automatically.

However, given its heritage with Hotmail and Live, Outlook.com is a service that can't be ignored. Fortunately, there’s an easy way to bypass these difficulties and limitations – by using Cronofy.

What is Cronofy?

Cronofy is a single API that works seamlessly across all calendar services. Not only does it provide an enhanced version of the Microsoft Outlook Calendar API, but it also includes all the other calendar service APIs like Microsoft Exchange and Apple iCloud. All you need is one account and one set of documentation for complete calendar integration with improved privacy and synchronization as standard.

Events and users aren’t capped, you only read the data you need, and we make it just as easy to use five different calendar APIs as one. Your users can continue using the calendar service of their choice and there’s no more work involved for you. The Cronofy API saves you time and hassle, ensuring your calendar integration is perfect and all users benefit from up-to-the-minute trustworthy information.

All the calendar services, easy integration, one API.

Microsoft Outlook Calendar API by Cronofy

Cronofy gives you all these benefits in addition to the standard features of the Outlook.com API:


Personal support

We’re here to answer your questions and help with any problems whenever you need assistance.


Global environment

Cronofy has been built for easy integrations across all languages and services, not just Microsoft and Windows.

High Uptime

99.95% uptime SLA

Cronofy is highly reliable, with a minimum average uptime of at least 99.95% guaranteed.

Active Development

Always in active development

The Cronofy API has been under active development since its creation, and we frequently release new features and list upcoming alpha features.

Calendar Compatibility

All-in-one API access

Get the full Outlook.com, Exchange, Office 365, iCloud and Google Calendar APIs all through Cronofy. Best of all, you only need one set of docs to make it happen.


Documentation for developers

Written by our own in-house development team, our API docs are logical, consistent, and concise. One set of Cronofy docs is all you need.

Data Modelling

Optimised data handling

Security and privacy are top priorities, so businesses and end-users can rest assured that data is handled legally and safely for all parties above and beyond the Outlook API’s standard.


Synchronization and scalability

One user or one billion, Cronofy scales to your requirements. Advanced synchronization means calendars that are always accurate.


Finely-tuned privacy

The standard Outlook.com API requires a lot of work to meet minimum privacy and security standards, and Cronofy’s better data modelling means peace of mind for developers, businesses, and end users.

Connect the world's calendars

Get instant access to our comprehensive docs, code libraries, tutorials, and much more.

We love the fact that once the integration was completed it will now be a simple process for our users to connect their accounts to Cronofy. Since we get users with varying IT skills it was important for us to keep the process quick and easy. Mission accomplished!

— Tapan Karambelkar, Product Manager, Resbook

Frequently Asked Questions

How do I get Outlook.com Calendar API access?

Sign up for a free Cronofy account and then follow our quick Getting Started tutorial that covers everything you need to know.

Where do I get my Outlook.com Calendar API key?

The Cronofy API key includes Outlook.com calendar API access as well as all the other major calendar APIs – sign in to your Cronofy account for instant access.

How much does Cronofy cost?

We’ve developed a scalable pricing system so that Cronofy is affordable whether you’re experimenting with a hobby project or designing a system for millions of users. If you’re just creating events, our API is free. It’s also free for the first twenty users you have. Beyond that, it’s one flat free without any charges for API transactions or events. See our pricing page for details.

Where can I see Cronofy being used?

As the Cronofy API plays a backend role in companies’ systems, we’ve created Sample Apps and Use Cases so you can get a better idea of what you can do with our API and how it works.

What programming languages are compatible with the Cronofy API?

You can code in whatever language you like; we have developers using C#, Java, .NET, PHP, JSON, and pretty much any language you can think of. If you’re using a common language like PHP or .NET, check out our code libraries.

How does the Cronofy API handle authentication?

It’s automatically managed on our side so there’s one less thing for you to do. A single Cronofy token for a user gives you the required access to all their calendar services.

What are Cronofy’s API limits?

We don’t put a fixed number of the amount of requests you can have, and we’re yet to see anyone come close to surpassing our current capabilities.

Can I replace the Outlook Calendar API with Cronofy?

Yes, your Cronofy API key replaces the Exchange, iCloud, Exchange, Outlook.com, Google Calendar, and Office 365 calendar APIs. Use any or all of them via Cronofy, the choice is yours.

I worked on a project that uses Cronofy’s API, what’s the best way to tell you?

Please tweet us (@cronofy) or email hello@cronofy.com - we love seeing your work.

I’m not a Microsoft-registered developer, can I still use the Outlook.com Calendar API with Cronofy?

Absolutely, you don’t need to be Microsoft registered, accredited, or certified in any way to use our API or the Outlook.com API.

I have another question, how can I contact you?

Feel free to email us any time and we’ll try to help! If you have a support query, please get in touch at support@cronofy.com. If you'd like to find out more about Cronofy or book a chat, please complete the form below or email hello@cronofy.com.

It's time to take the next step

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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

Find out more

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“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

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