My Two Dometrain Courses: Authentication in .NET and OpenID Connect
I now have two recorded courses on Dometrain. Dometrain is an online learning platform for software engineers, focused on .NET and C#. It was founded by Nick Chapsas, a Microsoft MVP known for his free .NET videos on YouTube.
I made them because, in my training, I have seen that many developers find authentication and OpenID Connect hard to understand. These two courses explain how they work, step by step.
The two courses are separate. You can take either one without the other.
Getting Started: Authentication and Authorization in .NET
This course came out in April 2026 and is about what happens inside ASP.NET Core when a user signs in. It starts with the user object, the ClaimsPrincipal and the request pipeline. Then it goes through the authentication middleware and its operations (Challenge, SignIn, Authenticate, SignOut and Forbid), schemes, tickets and data protection, and the cookie handler with its events and lifetimes. The last part is authorization: simple, role-based, policy-based and resource-based, plus custom requirements, handlers and authorization filters.
It is for .NET developers who want to understand how authentication in ASP.NET Core actually works.
Read more about the course or go to the course on Dometrain.
Getting Started: OpenID Connect
This course covers OAuth 2 and OpenID Connect at the protocol level, so it is not tied to .NET. It is for any developer who works with OpenID Connect, whether you use .NET, Java, Node.js or something else.
You look at the OpenID Provider, tokens and JWTs, ID tokens versus access tokens, claims and scopes. A large part is about how tokens are signed and validated, including key rotation. Then come the Authorization Code Flow, refresh tokens, state, nonce and PKCE, single sign-on and sign-out, the Client Credentials Flow, and OAuth 2.1.
If you want to read more about OpenID Connect first, see my free guide, OpenID Connect for Developers.
Read more about the course or go to the course on Dometrain.
Live training and consulting
If your team prefers to learn in a room together, I also teach both topics as live workshops on-site at your company: Authentication and Authorization in ASP.NET Core and Introduction to OpenID Connect and OAuth. For other topics, see my course catalog.
If you need help with your own setup, I also offer Duende IdentityServer and identity consulting.