What does the @Global() decorator do and how does it change module behaviour in NestJS?

Q: What does the @Global() decorator do and how does it change module behaviour in NestJS?

@Global() @Module({ providers: [ConfigService], exports: [ConfigService], }) export class ConfigModule {} // AppModule registers it once @Module({ imports: [ConfigModule] }) export class AppModule {} // ANY other module can now inject ConfigService without importing ConfigModule @Injectable() export class UsersService { constructor(private config: ConfigService) {} // works without importing ConfigModule } The module must still be imported once — usually in AppModule — to be registered in the container. After registration, its exports are available to every module without explicit imports. Only providers listed in exports are available globally — providers not exported remain private. Use @Global() sparingly — it hides dependencies and makes modules harder to test in isolation.

Difficulty: 5/10

global providers, module scope, dependency injection

@Global() registers the module's exported providers into the global DI scope. Any module in the application can inject those providers without listing the module in its own imports array. The global module must still be imported once — typically in AppModule — to be registered.

Global module registration and usage

Important rules for @Global():

1
The module must still be imported once — usually in AppModule — to be registered in the container.
2
After registration, its exports are available to every module without explicit imports.
3
Only providers listed in exports are available globally — providers not exported remain private.
4
Use @Global() sparingly — it hides dependencies and makes modules harder to test in isolation.

Scenario Questions

0-2 years experience

2-5 years experience

1During a sprint you refactor a shared LoggerModule to be global. After the change, a feature module that previously imported LoggerModule starts throwing a circular dependency error. Why might that happen?

Follow-up Questions