The Office 365 Contact API gives full access to a user's contacts and contact groups they have logged in Exchange Online. The Contact API can retrieve personal contact information such as email, address, name, phone number, and more. The API also allows developers to add a new contact or edit existing contacts. In order to access the Office 365 APIs, developers must first register their apps with Microsoft. All APIs use JSON with the Auth0 protocol for authentication, and Azure AD for authorization.