Why Dynamic API routes in NextJS? - Purpose & Use Cases

The Big Idea

What if one file could handle thousands of API endpoints automatically?

The Scenario

Imagine building a web app where you need a separate API file for every user or product ID, like /api/user1, /api/user2, and so on.

You have to create hundreds of files manually to handle each case.

The Problem

This manual approach is slow and messy.

It's hard to maintain, easy to make mistakes, and impossible to scale when new IDs appear.

Every time you add a new user or product, you must write new code files.

The Solution

Dynamic API routes let you write one flexible route file that handles many different URLs by capturing parts of the path as variables.

This means you write less code and your API automatically works for any ID without extra files.

Before vs After

✗ Before

pages/api/user1.js
pages/api/user2.js
// one file per user ID

✓ After

pages/api/[userId].js
// one file handles all user IDs dynamically

What It Enables

You can build scalable APIs that respond to many different inputs with just a few smart files.

Real Life Example

An online store where the API fetches product details based on the product ID in the URL, without needing a file for each product.

Key Takeaways

Manual API files for each ID are slow and unmanageable.

Dynamic API routes capture URL parts as variables automatically.

This makes APIs scalable, clean, and easy to maintain.