Swagger UI is integrated to ASP.NET Zero but disabled by default. Swagger UI configuration is located in Startup class in the .Web project. You can enable it by just uncommenting the related lines:
In Startup.ConfigureServices method, enable the following line:
services.AddSwaggerGen();
And in Startup.Configure method, enable the following lines:
app.UseSwagger();
app.UseSwaggerUi();
You can browse swagger ui with this URL: "/swagger/ui".
Thus, anyone (or any application) can explore, test and use the API easily.