---
author: ["Saurav Dhakal"]
title: "Understanding Separation of Concerns (SoC) in NestJS"
date: "2025-08-19"
summary: "A guide to understanding Separation of Concerns in NestJS using modules, services, and controllers."
tags: ["nestjs", "typescript", "architecture"]
categories: ["Backend Development", "NestJS"]
series: ["NestJS"]
ShowToc: true
TocOpen: false
---

When building applications, one of the most important design principles to keep in mind is **Separation of Concerns (SoC)**. NestJS, with its modular architecture, makes applying SoC almost effortless — but understanding _why_ it matters and _how_ to use it properly will help you write cleaner, testable, and future-proof code.

## What is Separation of Concerns and Why it Matters?

The basic idea is:

> A program should be divided into distinct sections, where each section addresses a single responsibility.
