Auth0 has released their SDK for Flutter applications:
However, it does not appear to have any built-in support for Web-based environments such as desktop Mac, Windows, or Linux.
Currently, we don’t have plan to provide direct support for additional platforms such as desktop/web.
However, the SDK does allow for additional platforms to be added by the community without Auth0 getting involved directly. And we have orchestrated it in such a way that makes that process a bit easier, with a separate platform interface library.
So basically, users of the SDK who need a layer to support a specific desktop/web platform would need to write that for themselves. This approach allows anyone in the community to provide support for any other platform and distribute it publicly for anyone to use in combination with our SDK.
We encourage you to submit feedback about the Flutter SDK here.