Top 20 NuGet authentication Packages

Classes to authenticate and communicate with the Instagram API. It also contains container classes which transform the JSON responses of the endpoints into objects.
GSSAPI implementation wrapper for .NET. Contains client implementation and additional WebRequest authentication modules.
A JwtBearer authentication provider for Nancy.
Provides easy JWT Authentication into your .NET, MVC and WebAPI projects.
External OAuth Provider for ok.ru
ASP.NET Core authentication middleware for OpenID 2.0 providers.
Middleware to initiate a proper identity in an aspnet core application when using azure appservice authentication.
Wilcommerce Authentication and Authorization library
Library with authentication models implementations
Proactive authentication AspNetCore package
Dead simple user authentication for C# with support for 2FA.
Behavior that handles a token un message header, between request
Basic tools for authentication
Site Extension to perform maintenance on ASP.NET User Authentication, Authorization, and Membership.
ASP.NET Core security middleware enabling Jira authentication.
A wrapper that allows you to use the iOS/Android Firebase Auth bindings (by Xamarin) from your netstandard library.
ASP.NET Web API utility library for JwtSharp.
ASP.NET Core utility library for JwtSharp.
This package contains an authentication handler for MPass implementing SAML 2.0 protocol for ASP.NET Core.