Microservices vs Monolith: When to Use Each Architecture

Microservices vs Monolith

The architecture debate. The answer always depends on team size, scale, and stage — not hype.

Monolith

Single deployable unit:
  Pros: simple dev/debug, easy transactions, fast,
        no network latency, low operational overhead
  Cons: scale all-or-nothing, large codebase,
        one bug affects everything, tech lock-in

Microservices

Each service independently deployed:
  user-service, post-service, search-service, notification-service

  Pros: independent scaling/deployment, tech freedom,
        fault isolation, team ownership
  Cons: distributed transactions complex, network latency,
        much higher operational overhead (k8s, mesh, monitoring)

The Migration Path

1. Start with a monolith — get to product-market fit
2. Use good module boundaries inside the monolith
3. Extract a service when you feel REAL pain:
   - One component needs 10x more scaling
   - Teams stepping on each other's code
   - Different language/tech requirements
4. Netflix, Uber, Amazon all started monolithic

Modular Monolith = best of both worlds
  Clear domain boundaries in code, single deployment
  Easy to extract a service later because boundary is clean