18 July 2019
Apple has started testing a new iCloud sign-in method on the web. The method ditches traditionally used username/password combination for using Face ID or Touch ID as a way for authentication. It was first spotted by 9to5Mac folks and is limited to beta users for the time being.
It means you will need to be having an Apple device running iOS 13 beta, iPadOS 13 beta or macOS Catalina beta. This is a must do step otherwise you will not be able to try out the new sign-in functionality. The next step is to visit the Safari browser on your device and access the iCloud beta website. Even if you don't enter the beta website URL, the regular iCloud URL should get redirected to the beta version automatically.
The beta website should offer you a pop-up mentioning that you can now sign-in using Face ID or Touch ID. It should be noted that the Face ID option will appear only if you have a device compatible with Apple's facial recognition tech. This way, you will be able to use your registered fingerprint or face to authenticate yourself. One thing to be kept in mind is that this method does not make use of the two-factor authentication. It is essentially the same as how you authenticate yourself and purchases on the App Store.
It is expected to be Apple's first move towards making Sign in with Apple mainstream on web services. As for how long it will remain in the beta stage, it is hard to predict. But it should become publically available by the time Apple releases stable version of all the new OS versions.