Support OAuth2 on .net core
At the moment, the OAuth2 Providers for ServiceStack library does not support .net core, as explained by mythz in this StackOverflow answer:
ServiceStack's OAuth2 depends on DotNetOpenAuth which unfortunately doesn't support .NET Core so there's currently no support for OAuth2 - https://stackoverflow.com/a/42344183/969613
Google Authentication is a feature requirement on my current project, so this one thing is preventing us from moving to .net core, support for this would be great.
The remaining OAuth2 providers have been rewritten in v5.5 without the Dependency to DotNetOpenAuth and are now in ServiceStack.Auth with the rest of the Auth Providers which all support .NET Standard 2.0/.NET Core
These new Auth Providers are available in the new Auth templates:
John Mckay commented
Dave Griffiths commented
One suitable library for this might be IdentityModel by Brock Allen.