The hidden cost of unorganized codebase (and how to fix it)
Practical tips for organizing codebase for long term maintainability
If you’ve been coding for a couple of years, you may know how painful it is to work in an unorganized code base.
You need to fix a critical bug that’s impacting your customers. So, you debug the issue. You start by searching for "payment" in your IDE and get 27 results scattered across UserService.js, PaymentManager.js, OrderHandler.js, and UtilityService.js. You open PaymentManager.js, a 1,200-line long file. After 20 minutes of scrolling, you find the bug is actually in a method called processUserData() inside UserService.js.
But wait, this method also handles email validation, and user preferences, and somehow manages shopping cart logic too.
Now you're afraid to change anything because you don't know what else might break. You spend another hour tracing through five different files just to understand what this one function does.
What should have been a 15-minute fix turns into a 3-hour investigation, and you're still not confident your change won't create new bugs.
Sound familiar? This is the hidden cost of an unorganized codebase.
It’s not just the time wasted, but the stress, the fear of breaking things, and the mental overhead of keeping track of scattered logic. New developers on your team face this confusion every single day.
An unorganized code base is a tech debt.
And if you ignore it long enough, it will drown your team in bugs and cripple your development velocity.
In this post, I'll walk you through 5 proven steps that will transform your chaotic codebase into a well-organized system. It will reduce the time to find files from hours to seconds or a few minutes.
1. Break down monster files first
I’ve seen a lot of GOD classes in most of the unorganized codebases I’ve worked on. Those files with more than 1000 lines of code. When developers don’t know where a piece of code should go, they add it to those monster files.
These monster files try to do too many things and violate the Single-responsibility principle. They also make unit testing painful, as you need a lot of setup and mocks for writing simple unit tests.
Therefore, break down those monster files into multiple files. Break them based on clear responsibilities. For example, if you have a huge file Main.js doing the following things:
Initialise other classes
Validate user details
Track order status
Contains logic to update the user’s preferences
Then, separate them into those individual responsibilities. This would give you immediate pain relief.
2. Organize by business domains
A few years back, I was trying to organize a messy legacy codebase. The files were organized in a flat structure and grouped by file types such as services, managers, repositories, etc. This flat structure made it time-consuming to find related files quickly when working on new changes. Also, it created a huge cognitive load for our developers to keep the scattered logic in their minds.
Therefore, I did some research to tackle this issue and came across the concept called Domain Driven Design (DDD). The term was coined by Eric Evans in his book Domain-Driven Design: Tackling Complexity in the Heart of Software, published in 2003. DDD is a software design approach that focuses on modelling software by decomposing it into domain models.
I won’t get into the terminologies of the DDD as they are vast (I may do it in another post). But, I will give you pragmatic tips to organize project using DDD:
Identify the core domains of your project. A domain means different areas or responsibilities of the software. For example, in an e-commerce app, domains could be products, orders, payments, users, shopping carts, and so on.
Use a common language that the project stakeholders (domain experts) agreed on while naming the domain. It helps to create a strong connection between the language and domain model. This naming process is called Ubiquitous language in DDD.
Create a directory for each domain and organize the codebase around it. In each domain, create sub-directories such as models, repositories, services, managers, etc. These sub-directories should contain respective files within the domain.
Add code that is shared by all domains in a shared directory.
When you work on a specific feature, you mostly change code related to that feature. So, organizing code by domains saves you time in navigating to multiple directories, which are far away, to find related files. You can easily find them in the same domain directory.
While Domain-Driven Design works best for complex applications, simpler CRUD apps might start with feature-based organization before evolving to full DDD.
3. Establish clear boundaries
When codes in different domains interact with each other directly, it creates tight coupling. A change in one domain requires a change in other domains too. Therefore, we need to define rules for what belongs in each domain and how domains can interact with each other.
The number #1 rule of domain-driven design is ownership. All the related files should live in the directory. For example, the /auth domain should contain all authentication-related functionalities such as login, registration, password reset, JWT handling, etc. This concept is called a bounded context in the DDD terminology.
The second rule is no direct interaction between different domains. The shopping cart domain cannot import methods directly from order management.
Events or interfaces should be used for interaction instead of loose coupling.
❌ Bad - shopping cart directly accessing order logic
import { OrderService } from '../order-management/OrderService'
✅ Good - using an interface
import { IOrderCreator } from '../shared/interfaces'
The third rule is that only truly generic functionality should go into the shared directory.
4. Create team standards
Whether you work in a small or large team, documenting and enforcing a consistent pattern could save you a lot of time. When there’s no style guide, every developer creates their own. It makes the codebase inconsistent and deteriorates quality over time.
Therefore, discuss with your team and create a coding style guide if you don’t already have one. The style guide should include information about code formatting standards, naming conventions, file structure, code organization, and so on.
For example, you can add the following information:
All domains must follow the kebab case (order-management, not OrderManagement)
Each domain should have consistent sub-directories like /services, /repositories, /models
If you want to go further, create a code review checklist for your team members to follow. The reviewer can ask questions like “Does this new code belong in the right domain?” during code reviews.
5. Gradually reorganize everything
It’s risky to reorganize the whole codebase at once. You may still be figuring out things at the beginning of codebase reorganization and don’t have a clear idea yet. The judgment of grouping a specific set of functionalities to make them more cohesive and loosely coupled requires practice and time.
So, take the time to experiment with the approach of organizing codebase by domains in a part of your codebase. Build clear boundaries between the domains. And also establish team standards so everyone follows the same approach.
After you have a clear understanding, scale the impact. Gradually reorganize the rest of the codebase to follow the domain-based organization approach.
Final thoughts
Working in an unorganized codebase not only slows you down but also drains your energy. It frustrates your team and makes every new feature feel like a risk.
But here's the good news: you don't need to fix everything at once. Start small. Pick your biggest, most painful file this week and break it down. Choose one domain area and reorganize it properly. Create one simple team standard.
These tiny, consistent refactoring steps compound over time. What feels overwhelming today becomes manageable tomorrow. It eventually becomes the foundation for sustainable growth.
Your action step: Before you close this newsletter, find one file over 400 lines in your codebase. That's your starting point.
Your future self (and teammates) will thank you.
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