Today we’re adding a new feature to the Google+ platform: application sign-in. Whether you’re building an app for Android, iOS or the web, users can now sign in to your app with Google, and bring along their Google+ info for an upgraded experience. It’s simple, it’s secure, and it prohibits social spam. And we’re just getting started.
Google says it focused on four key principles for this release:
1. Simplicity and security come first
If you sign in to Gmail, YouTube or any other Google service, you can now use your existing credentials to sign in to apps outside of Google. Just review the Google+ permissions screen (outlining the data you're sharing with the app, and the people who can see your activity), and you're all set. Google+ Sign-In also comes with the protections and safeguards you’ve come to expect from your Google account (like 2-step verification), so you can always sign in with confidence.
Managing your signed-in apps is easy too: visit plus.google.com/apps at any time, or open the new Google Settings app on Android.
2. Desktop and mobile are better together
Many developers offer web and mobile versions of their app, yet setting things up across a browser, phone and tablet is still a major hassle. Starting today, when you sign in to a website with Google, you can install its mobile app on your Android device with a single click.
3. Sharing is selective; spraying is just spam
Sometimes you want to share something with the world (like a high score), but other times you want to keep things to yourself (like fitness goals). With Google+ Sign-In and circles you decide who to share with, if at all. In addition: Google+ doesn’t let apps spray “frictionless” updates all over the stream, so app activity will only appear when it’s relevant (like when you’re actually looking for it).
4. Sharing is for doing, not just viewing
Pictures and videos are great for viewing, but sometimes you actually want to do stuff online. That's why, when you share from an app that uses Google+ Sign-In, your friends will see a new kind of "interactive" post in their Google+ stream. Clicking will take them inside the app, where they can buy, listen to, or review (for instance) exactly what you shared.
Google+ Sign-In is rolling out now on sites such as Fancy, Flixster, The Guardian, and USA Today.
Developers can get more information here.