mid.NET Core
What is Dependency Injection in .NET Core?
Updated Feb 20, 2026
Short answer
Dependency Injection (DI) is a design pattern used to achieve loose coupling by injecting dependencies into classes instead of creating them manually.
Deep explanation
.NET Core has a built-in IoC container. Services are registered in Program.cs and injected via constructors. It supports three lifetimes:
- Transient
- Scoped
- Singleton
Real-world example
Injecting a database repository into a controller instead of instantiating it manually.
Common mistakes
- - Incorrect service lifetime usage
- - Injecting scoped into singleton
Follow-up questions
- How would you scale this?
- What are trade-offs?