How to setup Retrofit with no baseUrl

just use like this

public interface UserService {  
    @GET
    public Call<ResponseBody> profilePicture(@Url String url);
}

source

From source (New URL resolving concept) you can simply specify whole path in post request.

Moreover we also can declare a full URL in @Post in Retrofit 2.0:

public interface APIService {

    @POST("http://api.nuuneoi.com/special/user/list")
    Call<Users> loadSpecialUsers();

}

Base URL will be ignored for this case.