Few architecture debates generate as much confident bad advice as monolith versus microservices. Ask a room of developers and you will hear two certainties that contradict each other: that a monolith is technical debt waiting to happen, and that microservices are needless complexity. Both claims are wrong in the same way. They treat the question as a matter of taste, when it is actually a matter of fit. The right architecture depends on the team, the domain, and the stage of the product. The same split that saves one organization will sink another.

Start with what each shape actually is, because the words get used loosely. A monolith is a single deployable unit that contains the whole application: the web layer, the business logic, and usually the data access, all in one codebase and one process. A microservices architecture splits the application into many small services, each independently deployable, each owning its own data, communicating over the network. The difference that matters most is not size.…