ASP.NET Core Identity is very good, though I prefer not using the default UI package because a) there's no easy way to disable any of the built-in pages, and b) I customize the UI so much that I might as well maintain my own code.

There are several IServiceCollection extension methods to configure Identity:

• AddDefaultIdentity<TUser>() used by ASP.NET Core Identity UI.
• AddIdentityCore<TUser>() which is called by AddDefaultIdentity<TUser>().
• AddIdentity<TUser, TRole>() used by IdentityServer4, which also calls AddDefaultTokenProviders().

I would prefer not to include Role so we don't have to deal with both role-based and claim-based authorization and remember which one is for what. That said, AddIdentity<TUser, TRole> does quite a bit more than the others, and at this point I'm not sure which of those extra things are required by IDS4, so I'm sticking with AddIdentity<TUser, TRole> for now.