Why I'm Choosing Vertical Slice Architecture

I've built with almost every common architecture pattern:

• MVC (Model-View-Controller): Fast to start, but controllers quickly turn into bloated "fat controller" messes.
• Factory & Adapter Patterns: Great in theory, but usually over-engineered when you only have one implementation.
• Clean / Layered Architecture: Separates everything into Controllers, Services, Repositories, and Entities. Changing a single feature means modifying 6+ different folders with endless boilerplate.

Layering your code by technical layers creates massive friction when shipping fast.

What is Vertical Slice Architecture (VSA)?

Instead of slicing code horizontally (putting all controllers in one folder,

all services in another, and all queries in a third), VSA slices code vertically by feature.

Each self-contained slice holds everything needed for a single request:

• Route endpoint
• Input validation schema
• Business logic
• Database query

1src/
2├── features/
3│   ├── auth/
4│   │   ├── login/
5│   │   │   ├── route.ts
6│   │   │   ├── schema.ts
7│   │   │   └── handler.ts
8│   │   └── register/
9│   │       ├── route.ts
10│   │       ├── schema.ts
11│   │       └── handler.ts
12│   └── billing/
13│       ├── checkout/
14│       │   ├── route.ts
15│       │   └── handler.ts
16│       └── webhook/
17│           ├── route.ts
18│           └── handler.ts

Why It Works

• High Cohesion: Everything for a feature lives in one place. No jumping between 6 folders to fix one bug.
• Low Coupling: Features don't touch each other. Editing or deleting register will never break billing.
• Effortless Deletion: Want to kill a feature? Just delete the folder. Zero leftover dead code across shared services.

Keeping Principles Intact (Without Over-Engineering)

• KISS (Keep It Simple, Stupid): Write straightforward code for each slice. No unnecessary abstraction layers.
• Pragmatic DRY (Don't Repeat Yourself): A little duplicated code across two slices is way better than a bloated "shared service" that breaks both.
• YAGNI (You Aren't Gonna Need It): Don't create generic helpers, wrappers, or interfaces until you actually need them.

Avoiding AI Slop & Retaining Control

AI tools love generating boilerplate: complex interfaces, redundant repository layers, and endless wrapper classes.

VSA keeps your codebase simple and linear:

Request -> Validate -> Run Logic -> Database Query -> Response

Because each slice is completely isolated, my thought process is faster, code stays clean, and everything stays directly in my control.

Quick Comparison

Summary

Vertical Slice Architecture gives you the speed of raw scripting with the modularity of clean code.

Keep features isolated, avoid premature abstraction, and ship fast.

Thank you for reading 💖