Understanding Monoliths, Microservices, and API Gateways
When we are building an application, we usually focus on creating features, databases, APIs, authentication, and building the frontend. But as the application grows, with an increasing number of users and features, managing everything inside a single application can become difficult. This is where architectural approaches come into the picture.
At this point, an important question is how should we structure the application itself? Should we keep all the features, business logic, APIs, and database interactions inside a single application, or should we split the system into smaller, independent services? These two approaches lead us to two common architectural patterns: Monolithic Architecture and Microservices Architecture. In this blog, we will understand how both architectures work, their advantages and disadvantages, and when it makes sense to choose one over the other.
Monolithic Architecture
A monolith is an application where all the major parts of the system live in a single codebase and are deployed as one unit.
Authentication, business logic, APIs, database operations, and other features can all exist within the same application.
The biggest advantage of a monolith is simplicity. It is generally easier to develop, test, debug, and deploy, especially when the application and development team are small.
However, as the application grows, the codebase can become harder to maintain. Scaling can also become inefficient because you may need to scale the entire application even when only one part of it requires more resources.
Microservices
Microservices take a different approach. Instead of building the entire application as one unit, we split it into smaller, independently deployable services.
Each service focuses on a specific business responsibility and can be developed, deployed, and scaled independently.
This provides benefits such as independent deployments, better scalability, and greater flexibility.
But microservices also introduce additional complexity. Services need to communicate over a network, which means we now have to deal with things like network failures, timeouts, retries, monitoring, and data consistency.
So microservices aren't simply a replacement for monoliths. They are useful when the benefits of independently managing services outweigh the additional complexity.
API Gateway
When an application consists of many microservices, clients shouldn't necessarily have to communicate with every service directly.
An API Gateway acts as a single entry point between clients and the backend services.
It can handle responsibilities such as:
Request routing
Authentication
Rate limiting
Logging
Request aggregation
Load balancing
For example, a client can send requests to the API Gateway, and the gateway decides which service should handle each request.
This keeps the internal structure of the backend hidden from the client and provides a central place for common API-related concerns.
Final Thoughts
There is no single architecture that is best for every application.
Monoliths prioritize simplicity, while microservices prioritize independent scaling and deployment.
The important part of system design isn't choosing the most complicated architecture. It's understanding the problem you're solving and choosing an architecture that makes sense for the application's current needs.