Integrating Google sign-in with a flutter desktop app is different from mobile apps because a popular flutter package named google_sign_in doesn't support desktop platforms yet.

This article will guide you on implementing Sign-in with Google for your Flutter desktop apps using OAuth2.0 protocol and desktop browser.

Here's what the OAuth 2.0 flow in Google SignIn looks like:

• User clicks on the “Sign in with Google” button in our app, which redirects them to Google’s 2.0 authorization endpoint.
• The user is prompted to log in to their Google account and grant permission for our app to access their data.
• If the user grants permission, Google redirects the browser to the redirect URI specified in the initial request, along with an authorization code.
• Our app sends a request to Google’s OAuth 2.0 token endpoint, along with the authorization code for an access token.
• Google returns an access token, which our app can use to authenticate requests to the corresponding Google service’s API.
• Our app can now make authorized requests on behalf of the user until the access token expires or is revoked by the user.

Table of Contents:

• Prerequisites
  • Set up the firebase project
  • Configure the OAuth client
  • Set up the flutter Project
• Let's Get Started
  • Add Dependencies
  • Import the dependencies
  • Getting Credentials
  • Obtaining OAuth2 Client and Access Token
  • Redirecting to the Authorization URL
  • Get Authorization Code from the request
  • Creating AuthCredentials for firebase authentication
  • Signing a user with AuthCredentials
  • Implementing Firebase Sign-out

For a step by step implementation guide, check out our canopas blog.