Keycloak

There is a gap in the OAuth 2.0 ecosystem that almost every team with a native mobile app eventually falls into. It does not have a widely agreed-upon name. It is not covered by any RFC. And yet, once you hit it, you quickly realize that everyone else has hit it too, and solved it differently.

The problem: your native app has a perfectly valid session. The user is logged in. Now you want to open a piece of web content (a WebView, an in-app browser tab) and have the user land there already authenticated. No second login screen. No friction.