Angular › Dependency Injection Providers & Injection Tokens

What does providedIn root mean when registering an Angular service?

Beginner

Answer

Setting providedIn to root tells Angular to make this service available application wide, using a single shared instance, without needing to manually list it in any component's or module's providers array. This is the most common and simplest way to register a service in modern Angular.

@Injectable({ providedIn: 'root' })
export class CartService {
  items: string[] = [];
}

// Now injectable anywhere in the app without any extra setup
constructor(private cartService: CartService) {}

Real-world example A shopping cart service registered with providedIn root is automatically available to every component across the entire app, sharing the exact same cart data everywhere it is injected.

Common follow-ups: What is the benefit of providedIn root over manually adding a service to a providers array?;How would you provide a service only for a specific feature area instead of the entire app?

Services & Dependency Injection;NgModules & Modular Architecture