Recetly switching from asp.net mvc to a web.api app and we had to serve some static files trough web api. However, web.api does not support serving selfing files on its own, for a good reason.
Web.Api was built on top of owin and is really only focused on serving web api requests. If you do not know about owin, I suggest you google about it right now, there is also an awesome training on pluralsight about it.
So as web.api is sitting on top of owin, this means we can easily integrate a static file middleware to our api pipeline.
To do so, simply install the Microsoft.Owin.StaticFiles package from nuget.
Now that you have static file middleware assemblies installed, you need to configure static folder you want to serve in your owin startup class.
If you do not already have a startup class, simply add one to your main assembly
Now have your startup file look like this
There you go, if you hit localhost/assets in your browser you should be able to get your assets.