Stop Adding a Service Layer to Every Web API

Service layers are often unnecessarily added to Web APIs. A service layer is only justified when orchestrating changes across multiple independent mutable systems (like a database and payment gateway). Most Web APIs write to a single database and read from multiple sources, making a service layer pure overhead. The one-to-one relationship between endpoints and service methods creates boilerplate code for DTO mapping, error translation, and localization without providing architectural value. The decision is simple: if your API doesn't orchestrate multiple transactional boundaries, skip the service layer and implement logic directly in endpoints.