In a WWDC online session, Apple said it was working to bring Face ID and Touch ID to the web via its Safari app for iPhone, iPad and macOS.
At the moment, Apple’s two methods of biometric authentication are only widely built into app sign in. If you access services via the web, you still have to tap in the search field and either type in your username and password or rely on an autofill service or password manager. These can be authenticated with Face ID or Touch ID but are at the end of the chain of a process rather than just being the authentication process itself.
The new feature is built on the common Web Authentication feature but has not been implemented on the web for iOS. It seems like a small update, but if your iPhone, iPad and Mac can authenticate you after first sign in with just your biometrics, it means you might not have to rely on storing all your sign in details with a password manager or Apple’s own Keychain.
Developers will have to build the feature into their websites, but adoption usually happens quite fast for Apple software. Expect to see it fairly soon.