Why I Stopped Using Monoliths for My Python Projects

Monoliths seem simpler — until they strangle your productivity and flexibility. I learned that the hard way.

Why I Stopped Using Monoliths for My Python Projects

It started like most developer journeys do — with a single Python file that slowly ballooned into a monolith.

At first, it felt productive.

Everything was in one place.

No need to switch contexts.

I could trace logic in a straight line and ship features quickly.

But over time, that convenience turned into chaos.

Here’s why I finally said goodbye to monoliths in my Python projects — and what I’ve learned since.

Monoliths Work… Until They Don’t

Let’s be clear: monoliths aren’t inherently evil. In fact, for small scripts, prototypes, or MVPs, a monolithic structure often makes sense.

But as a project grows, so does its complexity. Before long, I found myself stuck in these recurring problems:

1. Tight Coupling Everywhere

Changing one function meant unintended consequences in three other places.

Logic and data were so tightly coupled that even minor updates required cautious navigation and tons of testing.

2. Scaling Was a Nightmare

The single app was eating memory and CPU, and I couldn’t scale individual components.

Want to scale the image processing part without scaling the entire web layer? Good luck.

3. Onboarding New Developers Hurt

New teammates were overwhelmed.

“Where do I start?” they’d ask.

Explaining a 12,000-line monolith isn’t fun for anyone.

4. Testing Became Painful

Running tests meant loading the entire app, even for a small utility function.

Dependencies crept in where they didn’t belong.

CI pipelines got slower and more brittle.

Making the Shift: From Monolith to Modular

The breaking point came during a freelance project where the client needed a quick feature for just one part of the system. I realized I couldn’t isolate that feature without dragging in everything else.

So, I refactored the project into smaller, modular components — not full-blown microservices yet, but cleanly separated modules with clear responsibilities.

Here’s what I started doing differently:

Functional Boundaries First

Instead of a utils.py file that housed everything under the sun, I started organizing code by domain — user, auth, analytics, payments, etc. Each folder had its own models, services, and tests.

Dependency Injection for the Win

By injecting dependencies rather than hardcoding them, I made components more testable and flexible. Need a fake database for tests? Easy.

Reusable Packages

Whenever I spotted reusable logic — like logging, auth, or config management — I spun them off into small, standalone packages (sometimes published to my private PyPI).

Why This Approach Feels Better

Shifting away from monoliths made my codebase feel like a set of LEGO bricks instead of a Jenga tower. Here’s how that helped:

Faster Iteration: I could now make changes to individual parts without touching the whole system.

Clean Testing: Isolated modules meant faster and more focused unit tests.

Team-Friendly: Developers could work on different parts without stepping on each other’s toes.

Deployment Flexibility: In some cases, I could containerize and deploy modules independently.

Lessons (and Warnings)

That said, breaking up a monolith is not a silver bullet. Done poorly, it can lead to distributed monoliths — where everything looks separate but is still deeply coupled underneath.

So before you break things apart, ask yourself:

• Do the modules have clear boundaries and minimal dependencies?
• Are you doing it for scalability or just because “microservices are cool”?
• Can you test and deploy modules independently?

If you don’t need the complexity, it’s okay to keep things simple.

Final Thoughts

Monoliths had their place in my early projects, but as my codebases (and teams) matured, the costs outweighed the benefits.

Today, I think modularly from day one — not necessarily jumping into microservices, but always designing with separation of concerns in mind.

If your Python project is starting to feel like a tangled mess, it might be time to rethink your structure.

You don’t need to go full microservices. Just start by breaking the monolith into meaningful modules.

Your future self — and your teammates — will thank you.

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