Registering Services for IEnumerable Injection Service Registration Fundamentals Service registration is the process of telling the DI container how to create instances of a service, typically done at application startup. Registering Services for IEnumerable When services implement a common interface, you can register them in such a way that the DI container can provide an IEnumerable of these services. In .NET, for example: services.AddTransient<ICommonService, ServiceA>(); services.AddTransient<ICommonService, ServiceB>(); Why would you register mulitple instances of the same interface? One use-case is that it is the same service with a different configuration. Here is an example of how that would look: services.Configure<CustomOption>("Opt1", configuration.GetSection("Options1")); services.Configure<CustomOption>("Opt2", configuration.GetSection("Options2")); builder.Services.AddSingleton<ICommonService,Servic