Mix web api controllers and site controllers

Problem is I can’t name the web api controllers the same as my existing controllers.

You could have your API controllers with the same name as your existing controllers. Just put them in a different namespace to make the compiler happy.

Example:

namespace MyAppName.Controllers
{
    public class ProductsController: Controller
    {
        public ActionResult Index()
        {
            var products = productsRepository.GetProducts();
            return View(products);
        }
    }
}

and the API controller:

namespace MyAppName.Controllers.Api
{
    public class ProductsController: ApiController
    {
        public IEnumerable<Product> Get()
        {
            return productsRepository.GetProducts();
        }
    }
}

and then you have: /products and /api/products respectively to work with.