Dependency Injection in C#: Singleton, Scoped & Transient

 Dependency Injection in C#: Singleton, Scoped & Transient

When building modern .NET applications, Dependency Injection (DI) is at the heart of clean architecture. But one of the most important decisions is choosing the right service lifetime. Let’s break it down 👇

🔵 Singleton
One instance for the entire application.
Use it when the service is stateless and can be safely shared across the whole app.

✔ Great for stateless services, caches, or configuration loaders.
⚠ Be careful with shared state and thread-safety issues.

🟢 Scoped
One instance per request.
Use it when you need one clean instance per HTTP request.

✔ Ideal for business logic and data-related services used throughout a single HTTP request.
✔ This is the default choice for many web scenarios.

🟠 Transient
A new instance every time it's requested.
Use it when the service is lightweight and must be fresh every time.

✔ Useful for lightweight, stateless services.
✔ Safest lifetime when you're concerned about multithreading side-effects.

👇Which lifetime do you use the most in your .NET projects — and why?