Google People API
Provides access to Google Contacts data including creating, reading, updating, and deleting contacts and contact groups, searching contacts, and accessing profile information.
Documentation
Documentation
https://developers.google.com/people/api/rest
Authentication
https://developers.google.com/people/v1/how-tos/authorizing
GettingStarted
https://developers.google.com/people/v1/getting-started