Choosing between a monolithic architecture and a microservices architecture is one of the most important decisions in software development. Each approach has strengths, weaknesses, and ideal use cases. The right choice depends on the size of your project, its growth stage, and technical requirements.
When to Use a Monolith
A monolithic application is a single unified codebase where all features and logic live together.
Monoliths are often used by startups and small teams because they are simple to get started with. However, as the company grows, it is usually recommended to migrate to microservices to achieve greater scalability.
That said, there is no absolute rule: each project has its own needs, and the architecture should adapt to them.
Advantages of Monoliths
- Easy to develop: simple structure and straightforward setup.
- Easy to debug: all code in one place speeds up troubleshooting.
- Easy to deploy: one build, one deploy.
- No latency issues: everything runs in the same process.
Disadvantages of Monoliths
- Scalability limitations: as the system grows, it becomes harder to manage.
- More prone to failures: one bug can affect the entire application.
- Costly releases: large updates demand more time and resources.
When to Use Microservices
A microservices architecture splits the system into independent services, each responsible for a specific function.
Examples of companies that use microservices:
- Netflix uses microservices for search, recommendations, and streaming.
- Mercado Libre structures payments, deliveries, and digital wallet as separate services.
This separation allows teams to scale and innovate faster, but it adds complexity to the system.
Advantages of Microservices
- Independent deployments: each team can release features without impacting the whole system.
- Scalability: services scale individually according to demand.
- Technology flexibility: different languages and frameworks can be used per service.
- Better observability and resilience: issues are isolated.
- Faster iteration: small teams can deliver changes quickly.
Disadvantages of Microservices
- Higher management complexity: requires advanced monitoring and communication practices.
- Latency between services: depends on gRPC, messaging, or APIs.
- Higher initial costs: infrastructure and DevOps require more investment.
- Harder to debug: errors can spread across distributed services.
- Local development challenges: running multiple services usually requires Docker or orchestration.
Migrating from Monolith to Microservices
The migration from a monolith to microservices can be simple or extremely complex — it all depends on how the monolith was built.
- Clean architecture and design patterns make migration easier.
- Tightly coupled and repetitive code increases difficulty.
- Asynchronous processes in supported languages allow delaying migration in some flows (such as email sending or performance-heavy tasks).
Final Considerations
- Use monoliths if you are a startup, have a small project, or are validating a product.
- Use microservices when you need scalability, independent deployments, and to deal with complex domains.
But the opposite can also happen. There are cases where systems are born in microservices and later migrate back to a monolith because it makes more sense. A famous example is Prime Video, from Amazon.
Even though it is a service that serves millions of users and integrates with hundreds of external systems, the team concluded that, for them, it made more sense to return to a monolithic architecture. This shows that rules are not always universal — the best choice is always the one that fits the context of your business and your team.
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