What are some ADFS alternatives for doing single sign on for an ASP.NET app with users in active directory?

Question

Needs to be secure and able to handle thousands of users.

Answer 1

Check out ADAM and AzMan.

ADAM is Active Directory Application Mode. There is a how-to guide at: http://msdn.microsoft.com/en-us/library/ms998331.aspx

AzMan is Authorization Manager. There is a how-to guide at: http://msdn.microsoft.com/en-us/library/ms998336.aspx

Answer 2

Microsoft is replacing ADFS with a brand new Identity framework, Zermatt. It is actually quite nice. You might also check out Ping Identity if you are open to a commercial product.

Here is a blog post discussing various alternatives. If you decide you want to investigate Zermatt more deeply, see this post.