.NET Core Identity与IdentityServer4选型咨询：需登录注册及第三方登录

Great question—this is a super common point of confusion, so let’s break down the roles of each tool clearly and map them to your project needs.

First: What Each Tool Actually Does #

Let’s get the basics straight to avoid mixing up their purposes:

• .NET Core Identity: This is your built-in user management workhorse. It handles local user registration/login, password storage/reset, role-based access control, and even integrates with external logins (Google, Twitter, etc.) out of the box. It’s tightly tied to your app’s user database and exists to manage identities within your application.
• IdentityServer4: This is a standalone identity provider (IDP) built on OAuth2 and OpenID Connect standards. It’s designed for distributed systems—think multiple apps (web, mobile, desktop) and microservices that need a single, centralized source of truth for authentication. It handles things like single sign-on (SSO), issuing standardized JWT tokens for API access, and managing third-party app permissions to your services.

For Your Specific Project: Stick with .NET Core Identity #

Your requirements (local login/register, API import/export, Google/Twitter logins) are fully covered by .NET Core Identity—you don’t need IdentityServer4 here. Here’s why:

• Local auth workflows: Identity’s scaffolded pages (or custom implementations) handle registration, login, and password management without extra setup. You can even customize the UI to match your app’s design easily.
• External logins: Adding Google/Twitter support takes minutes. Just configure AddAuthentication() with AddGoogle() or AddTwitter() in your Program.cs (or Startup.cs for older .NET versions). Identity handles the entire OAuth flow and links external accounts to your local user records automatically.
• API protection: If your API is part of the same project (e.g., an MVC app with API endpoints), you can use Identity’s cookie authentication to secure them. If you’re building a separate frontend (like React/Vue) that calls your API, Identity can generate JWT tokens for users to authenticate requests—no external IDP required.

When Would You Need IdentityServer4? #

Only reach for IdentityServer4 if you hit one of these scenarios:

• You have multiple independent applications (e.g., a web app, a mobile app, and a set of microservices) that need single sign-on (users log in once and access all apps without re-authenticating).
• You need to let third-party applications access your API securely (using OAuth2 flows like client credentials or authorization code).
• You want to decouple your authentication logic from your business apps—turning identity management into a standalone service that all your apps rely on for consistency.

Final Recommendation #

Since you want the simplest way to build your app correctly, go with .NET Core Identity. It’s lightweight, integrated directly into your .NET Core project, and covers every requirement you listed without adding the complexity of a separate identity server.

内容的提问来源于stack exchange，提问作者ferdinand