Differences between AddTransient, AddScoped and AddSingleton Services in ASP.NET Core

Transient

ASP.NET Core will create and share an instance of the service every time to the application when we ask for it. The service can be added as Transient using AddTransient method of IServiceCollection. This lifetime can be used in stateless service. It is a way to add lightweight service.

This service always returns new instance for each request        

Singleton

ASP.NET Core will create and share a single instance of the service through the application life. The service can be added as a singleton using AddSingleton method of IServiceCollection. ASP.NET Core creates a service instance at the time of registration and subsequent requests use this service instance. Here, we are not required to implement a Singleton design pattern and single instance maintained by the ASP.NET Core itself.

This service always returns single instance for all and individuals request        

Scoped

ASP.NET Core will create and share an instance of the service per request to the application. It means that a single instance of service is available per request. It will create a new instance in the new request. The service can be added as scoped using an AddScoped method of IServiceCollection. We need to take care while the service is registered via Scoped in middleware and inject the service in the Invoke or InvokeAsync methods. If we inject dependency via the constructor, it behaves like a singleton object.

This service always returns new instance thoughout the request as a scope.