How to implement SAML or (SSO) similar authentication methods in flutter?

I had been searching for the SAML implementation in Flutter, but I didn't get desired results. I learned that SAML is a browser-based security system, but I didn't get how I can implement SAML in a flutter.

If not SAML so what would be the alternative?

I will be very thankful for any help and suggestions.

There are two main standards to authenticate: Saml and OAuth. Saml is an old, stable, complete and largely supported standard everywhere on the web, in public services and enterprises (xml). OAuth/OpenId is a recent standard (rest/json) controlled by some big advertising companies and mainly designed for end user consumers.

The only issue of Saml is that it was universal but designed for the web, not for devices. But nowadays, many web sites are encapsulated inside device applications, so Saml is less trendy. And overall, the big advertising companies don't want Saml and provide only OAuth.

So Flutter is a Google toolkit and OAuth is controlled by Google in particular. And Google wants to keep control on you and all enterprises and public services, so Google tries to complicate authentication with other standards, so does not provide a simple way inside Flutter to authenticate/authorize with Saml.

In your case, you need to use third party packages to implement Saml inside the app. There was a package to authenticate via Saml on Flutter on https://devcodef1.com/news/1014561/implementing-saml-in-flutter but it seems no more usable and there are no simple package on https://pub.dev/packages?q=saml.

Anyway, as a client app, Saml just requires a redirection to the authentication page of the identity provider. In fact, you just need to include a webview to get the credentials and to share them between the client app, the server service, and the identity provider.