We are excited to announce Outlook REST APIs for mail, calendar, and contacts now support both Office 365 & Outlook.com! This single REST API endpoint
https://outlook.office.com/api combined with a new app registration portal and v2.0 app model announced by the Azure Active Directory team, makes it very easy to build a single app that can be used by both Office 365 and Outlook.com users.
As previously announced, we are upgrading Outlook.com users to a new Office 365-based infrastructure. As users are upgraded, apps can use Outlook REST APIs to access these users’ mailboxes. This new platform will enable developers to reach 400 million monthly active Outlook.com users, in addition to tens of millions of Office 365 users. If your app utilizes both REST APIs and our add-in platform, you are all set as we also support Outlook Add-ins for Office 365 and Outlook.com users.
You will find more information in an overview of the Unified Outlook Service API and getting started instructions for multiple platforms at https://dev.outlook.com. Please note that the new OAuth endpoint is in preview and you can check here for details on what is and isn’t supported during Preview.
Please go ahead and try our REST APIs out and let us know your feedback by posting to UserVoice. The new API endpoint and app registration portal are a direct result of the feedback from our developer community. We look forward to seeing many awesome apps being built using the unified Outlook API endpoint to delight Office 365 & Outlook.com users!