Monoliths vs. Monorepo: Clearing the Confusion
In the world of software engineering, two terms often come up in architecture discussions: monoliths and monorepos. They sound similar, and many people mistakenly use them interchangeably. But here’s the kicker — they’re fundamentally different concepts that solve entirely different problems.
In this blog, we’ll break down what monoliths and monorepos actually mean, highlight their differences, and explore three real-world examples to show when and why you might choose one over the other.
What is a Monolith?
A monolith refers to the architecture of an application. In a monolith, all parts of the application — frontend, backend, and database — are tightly integrated into a single codebase.
Characteristics:
• Single deployable unit: All components are built, tested, and deployed together.
• Tightly coupled: Changes in one part of the system can directly affect others.
• Best for: Simple or smaller-scale applications where components are closely related.
Example:
An early-stage startup builds a food delivery app where user authentication, menu display, and order placement are part of one unified system.
What is a Monorepo?
A monorepo refers to the repository structure used to organize code. In a monorepo, all services, libraries, and projects are stored in a single repository, regardless of whether they belong to the same application.
Characteristics:
• Shared codebase: Teams working on different projects can access shared libraries and modules.
• Independent services: You can still deploy each service separately, even if they’re in the same repo.
• Best for: Large organizations with multiple teams working on interrelated projects.
Example:
An e-commerce company has separate teams working on multiple mobile apps, like customer facing app, a warehouse management system, etc. They store all code in a single repository to reuse components like authentication and payment services.
Key Differences
Where Confusion Creeps In
The confusion often arises because both terms imply “togetherness”:
• A monolith brings all application components together as one unit.
• A monorepo brings all codebases together in a single repository.
But you can have:
• A monolith in a monorepo (e.g., a single app with tightly integrated features stored alongside other projects).
• Microservices in a monorepo (e.g., independent services stored in one shared repository).
• A monolith in multiple repos (e.g., a frontend repo and a backend repo for one tightly coupled app).
It’s crucial to understand the problem you’re solving — application architecture vs. code organization.
Real-Life Practical Examples
- Small Startup with a Monolith in a Single Repo
Scenario:
A small team of developers is building an MVP for a fitness tracking app. They decide to use a monolithic architecture for simplicity and store all code in a single repository.
Why it works:
• The monolith reduces complexity for this small-scale project.
• A single repo makes it easy for the team to collaborate.
Outcome:
The startup launches quickly, and the monorepo ensures seamless access to all code as they iterate on the app. - Enterprise Adopting Microservices with a Monorepo
Scenario:
A global e-commerce company is transitioning from a monolithic architecture to microservices. To improve collaboration, they move all services to a monorepo.
Why it works:
• Teams can reuse shared components like authentication and payment modules.
• Each microservice is independently deployable while still being part of the same repo.
Outcome:
The monorepo reduces duplication and ensures consistency across services while supporting the flexibility of microservices. - Hybrid Approach: Monolith in Multiple Repos
Scenario:
A mid-sized SaaS company builds a monolithic product for project management. The frontend and backend are tightly integrated but stored in separate repositories for better team ownership.
Why it works:
• The monolithic architecture simplifies application development.
• Separate repos allow the frontend and backend teams to focus on their respective areas.
Outcome:
The team avoids operational overhead while maintaining clarity in code ownership.
How to Choose the Right Approach?
When deciding between monoliths and microservices or monorepos and multiple repos, ask yourself:
1. What’s your application’s complexity?
• For simple apps, monoliths are fine.
• For complex, growing apps, microservices may be better.
2. How is your team structured?
• Small teams benefit from monoliths in single repos.
• Large, cross-functional teams thrive with microservices in monorepos.
3. Do you have shared components?
• If multiple projects rely on shared libraries, a monorepo can simplify development.
Key Takeaways
• A monolith is about how you build your application.
• A monorepo is about how you organize your code.
• The two are not mutually exclusive. You can mix and match based on your needs.
The best choice always comes down to your use case, team size, and future plans. By understanding the differences and trade-offs, you can make informed decisions that set your team up for success.
