Authorizing Your App with Gmail

All requests to the Gmail API must be authorized by an authenticated user. Gmail uses the OAuth 2.0 protocol for authenticating a Google account and authorizing access to user data. You can also use Google Sign-in to provide a "sign-in with Google" authentication method for your app.

Why use Google for authentication?

Providing OAuth 2.0 user authentication directly or using Google+ Sign-in reduces your development overhead. It also provides a trusted and secure login system that's familiar to users, consistent across devices, and removes the burden of users having to remember another username and password.

If your public application uses scopes that permit access to certain user data, it must complete a verification process. If you see unverified app on the screen when testing your application, you must submit a verification request to remove it. Find out more about unverified apps and get answers to frequently asked questions about app verification in the Help Center.

How authorization works

At a high level, all apps follow the same basic authorization pattern:

1. During development, register the application in the Google API Console.
2. When the app launches, request that the user grant access to data in their Google account.
3. If the user consents, your application requests and receives credentials to access the Gmail API.
4. Refresh the credentials (if necessary).

Get started

To get started, see Implementing Server-side Authorization.