Monolith vs Microservices - When to use each
FEATURED ATTACHMENT When we talk about software development, many doubts and discussions come up — like which programming language is better, which database to use, or even how to deploy the application. That’s normal.
The real problem is when people take sides and only see one perspective.
This happens a lot!
I was on Twitter and saw a big discussion thread about Which is better: monolith or microservices?
So, this article is to share my opinion on the topic.
The Beginning
Before this type of discussion existed, there was already a way to build applications, and that way is called Monolith.
Monolith was conceived first because, most of the time, it’s a simpler architecture (though that’s not always the case). Let’s understand what exactly a monolith project is:
Understanding a monolith
E-commerce Monolith Architecture
This is an example of an e-commerce application. To better explain what’s happening, we have this e-commerce split into three parts:
- Frontend: what the end user sees and interacts with
- Backend: where all the application logic lives
- Database: where all the data and information of our e-commerce is stored
So, this is a single system with all modules and functionality within it. One project, one codebase, one database, one programming language!
Good Points
That singularity brings us many advantages:
Without Monolith
Scattered development without unified structure
- Multiple codebases to manage
- Different patterns in each service
- Complex deployment orchestration
- Technology fragmentation
With Monolith
Unified development with consistent structure
- Single repository, single codebase
- Consistent patterns and logic
- One deployment pipeline
- Rapid development cycle
Monolith has a lot of good points.
Imagine that our e-commerce has all these functionalities:
E-commerce Features (All in One)
It’s a great application, right? We have many functionalities coupled together, and this brings us to the first problem of monoliths…
Bad Points
As I said, all functionalities are highly coupled, which means that if one functionality breaks, all the others break too.
When Notifications Break...
Notification Service Crashes
An unhandled exception occurs in the notifications module.
Backend Goes Down
Since everything is in the same process, the entire backend crashes.
All Services Unavailable
Auth, Products, Cart, Payments, Shipping — everything stops working.
Users Can't Access Anything
Complete service outage. Users see error pages everywhere.
In our example, the notification functionality had a problem, and because of it, the entire application is down.
Unfortunately, this isn’t the only problem with monolith applications…
Monolith Challenges
Issues that arise as the application grows
- Scaling requires duplicating the entire app
- Codebase grows exponentially
- Single point of failure
- Deployment = everything or nothing
What You Need
Ideal characteristics for large-scale systems
- Scale only what needs scaling
- Smaller, manageable codebases
- Isolated failures
- Independent deployments
The Present
Looking at these problems, software architects wanted to find a better way to build software, so they came up with a solution.
The term “microservices” was coined in May 2011 during a software architects conference to represent a style of system architecture. The microservices-oriented architecture proposal is to develop systems that are more flexible, scalable, and simpler to maintain than monolithic architectures.
But the first question is: how exactly does it work?
Understanding microservices
In a microservices architecture, modules and functions are split apart. It’s as if each service is a standalone application. See the example below:
Microservices Architecture
🐳 Each runs in its own container
🔀 Communicate via APIs/Events
📈 Scale independently
Notice how each service is completely independent:
- Different technologies: Each team chooses what works best (Node, Go, Python, Java, Rust, C#)
- Own database: No shared state between services
- Isolated deployment: Deploy one without touching others
Observations
Microservices are occasionally misconstrued as Pattern-Oriented Software Architecture (POSA); however, it’s essential to recognize that they are distinct concepts.
The company RedHat says this about it:
The main characteristic that differentiates them is scope: SOA is an architectural approach adopted by the enterprise as a whole, while microservices are an implementation strategy of the development team for each application.
With that in mind, let’s continue.
Good Points
A major advantage of microservices architecture is that if one microservice stops, the entire application doesn’t break!
When Notifications Break in Microservices...
Notification Service Crashes
The notifications microservice encounters an error.
Other Services Keep Running
Auth, Products, Cart, Payments — all continue working normally.
Graceful Degradation
Users can still shop, pay, and use the app. Only notifications are delayed.
Easy Recovery
Ops team restarts just the notification service. No full redeploy needed.
Here we can see that if one of the microservices breaks, the others keep working. This is great because it brings us more consistency and reliability.
Microservices bring many benefits:
Monolith Limitations
What you're limited to with monolithic architecture
- One massive codebase for everything
- Complex code that's hard to understand
- Deploy everything at once
- Stuck with one programming language
Microservices Benefits
What microservices architecture enables
- Smaller, focused codebases
- Each service is easy to understand
- Deploy services independently
- Use the best language for each service
As you can see, microservices have many advantages and are used to some extent by almost every large tech company nowadays, since they provide many capabilities for organizations to scale their systems properly.
Bad Points
Unfortunately, microservices aren’t perfect. This software architecture has problems, so let’s talk about some of them.
Microservices Complexity
Distributed System Challenges
Network calls can fail. Latency becomes a concern. Debugging across services is hard.
Deployment Overhead
Each service needs its own CI/CD pipeline, monitoring, and infrastructure.
Data Consistency
Keeping data in sync across services requires careful design (sagas, event sourcing).
Increased Costs
More services = more servers, more monitoring, more operational complexity.
Microservices are usually complex. They need to be very well planned and executed because, if not, the software can become insecure, vulnerable, and hard to understand as a whole.
The truth is, microservices are excellent but can also be a shot in the foot.
The Future?
So, to finally answer the awaited question… Which is better?
In my opinion, it depends on the situation :)
Use Monolith When
Scenarios where monolith makes more sense
- Small team (< 10 developers)
- Simple business logic
- MVP or early-stage startup
- Limited budget for infrastructure
Use Microservices When
Scenarios where microservices shine
- Large team with multiple squads
- Complex, evolving business rules
- High scale requirements
- Need for independent deployments
We, as developers, need to be smart when choosing one architecture over another. For example, it’s not smart to use microservices architecture for a website for a small local store because the development will be slower, the website probably won’t have complex business rules, and it will be more expensive.
Conclusion
It’s important to always be open-minded. Microservices have become mainstream in software development, but that doesn’t mean we should only use them. There are other types of software architecture like Component-Based Architecture, Service-Oriented Architecture (SOA), Layered Architecture, and others.
I think a good developer must understand when to use one or the other.
Contact me and tell me what you think about this article!
Hope you liked it.