Microservices vs Monolith

The "Microservices" hype train has been running for a decade, but many teams are now getting off at the "Modular Monolith" station.

Microservices promise decoupling, scalability, and autonomy. The theory is great: Team A works on the Billing Service, Team B works on the User Service, and they never step on each other's toes. However, the reality for many startups is "Distributed Monoliths." You end up with the complexity of a distributed system—network latency, eventual consistency, distributed tracing hell—without the team size to manage it.

The Complexity Tax

Every time you split a service, you introduce a network boundary. Function calls that took nanoseconds now take milliseconds and can fail. You now need service discovery, a message bus (Kafka/RabbitMQ), circuit breakers, and complex CI/CD pipelines to coordinate deployments. If your team is under 20 engineers, this operational overhead often cripples feature velocity.

The pragmatic alternative is the Modular Monolith. You build a single deployable unit (simpler ops) but strictly enforce boundaries within the code. The "Billing" module has its own folder and database tables, and the "User" module can only interact with it via a defined public interface. You get the code organization benefits of microservices without the infrastructure nightmare.

When to Split?

So when should you use microservices? 1. Independent Scaling: If your Video Processing module eats 90% of CPU but the rest of the app is idle, split it out. 2. Organizational Scaling: If you have 100+ devs and deployment queues are hours long, splitting allows teams to deploy independently. 3. Technology Diversity: If one specific problem is best solved in Rust while the rest of the app is Node.js.

Start Monolithic. Extract later. Premature microservices are the root of much engineering evil. It's much easier to slice a well-structured monolith than to glue together a shattered distributed system.