What is the difference between app.use() and NestJS middleware?

Q: What is the difference between app.use() and NestJS middleware?

@Injectable() export class LoggerMiddleware implements NestMiddleware { constructor(private readonly loggerService: LoggerService) {} use(req: Request, res: Response, next: NextFunction) { this.loggerService.log(`${req.method} ${req.url}`); next(); } } @Module({ imports: [LoggerModule] }) export class AppModule implements NestModule { configure(consumer: MiddlewareConsumer) { consumer .apply(LoggerMiddleware) .forRoutes({ path: '*', method: RequestMethod.ALL }); } } app.use() — functional middleware, no DI, registered globally. NestJS middleware — class-based, supports DI, can be scoped to specific routes. NestJS middleware can be excluded from specific routes using .exclude(). Use app.use() for simple third-party middleware (helmet, cors, compression).

Difficulty: 5/10

middleware, request pipeline, NestJS integration

app.use() registers Express/Fastify middleware directly — it works but bypasses NestJS DI so it cannot inject services. NestJS middleware classes implement NestMiddleware, are decorated with @Injectable(), and are applied via configure() in a module implementing NestModule — allowing them to use injected services.

NestJS middleware with DI

Key differences:

1
app.use() — functional middleware, no DI, registered globally.
2
NestJS middleware — class-based, supports DI, can be scoped to specific routes.
3
NestJS middleware can be excluded from specific routes using .exclude().
4
Use app.use() for simple third-party middleware (helmet, cors, compression).

Scenario Questions

0-2 years experience

1You need to log every incoming request in a NestJS project that uses the default Express adapter. Would you use app.use or a Nest middleware, and why?
2If you add an app.use that parses JSON bodies before Nest's built‑in body parser, what effect does it have on a controller that expects a DTO?
3How would you register a simple authentication check that runs for all routes using app.use versus Nest middleware? Walk me through the steps.

Follow-up Questions

Can you walk me through how Nest's DI container resolves a middleware class?
What would happen if you placed an app.use after Nest's global exception filter?
How does the order of middleware registration affect route handling in NestJS versus Express?