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Microsoft 365

Add-ins for—build an experience that reaches 400 million users

We are thrilled to announce that Uber, Boomerang and PayPal are among the first partners to bring add-ins to our 400 million active users—leveraging the new unified consumer and commercial Outlook APIs announced earlier today at Build.

The Outlook APIs create an open platform for developers to build contextual experiences for and Office 365 users that simplify everyday tasks, helping them get more done without the hassle of switching between multiple applications.  Here’s an early peek at what Uber and Boomerang will bring to our users this summer.

  • Uber—Need a ride to your meeting or event? No problem, set up an Uber ride reminder for any calendar event with a single tap.
  • Boomerang—Send messages at the perfect time, get a reminder if your email doesn’t receive a response, and add a smart calendar assistant that lets you schedule meetings and share your real-time availability, all without leaving your email.

We’ll have more information to share about the PayPal experience, as well as other third-party partner announcements, in the near future.

Build your add-in today

Add-ins are easy to build with open standards like HTML, CSS3, and JavaScript for user interfaces, with the option to integrate further using REST APIs and OAuth for secure access to data and services – all delivered to a global audience of and Office 365 customers. And best of all, developers get the benefit of write once, run anywhere technology, meaning their apps will work in, Outlook Web App and Outlook desktop.

If you’re one of the many developers at Build, stop by the Office 365 booth and talk with the team about our new Napa development tools that make it easy to get started. Also be sure to visit the teams from Uber and Boomerang to get a closer look at what they’re working on.

For everyone else, go to and see how to get started with add-ins for Outlook today.


—Pretish Abraham, principal program manager lead on the Outlook team.


Frequently asked questions

Q. I want to get started building an add-in targeted at consumers on  Is there any way I can test the add-in on right now?

A. We have a limited number of developer accounts available.  Please visit for details on how you can request an account.

Q. Can the same add-ins really be used across, Outlook 2013 and Outlook Web App?

A. Absolutely, add-ins for Outlook let you reach your users on any of these applications.

Q. Will add-ins be available for users in all markets?

A. Add-ins will be available worldwide, but availability of individual add-ins is dependent on the publisher.

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