Next.js API Routes vs Route Handlers: When to Use Each

Next.js is a popular framework for building web applications. Understanding how to effectively use its features is important for developers. One key area of focus is the difference between API routes and route handlers. Both allow developers to create server-side endpoints, but they do so in different ways. Let's break down these differences and help you decide when to use each.

What are Next.js API Routes?

Next.js API routes are part of the Pages Router. You can find them in the pages/api directory of your Next.js project. Each file in this directory corresponds to an API endpoint.

These routes use NextApiRequest and NextApiResponse, which are thin wrappers around Node.js's IncomingMessage and ServerResponse. This means that the runtime for API routes is always Node.js.

A key feature of API routes is that they do not support static caching. Every request triggers the serverless function, meaning that you must manually set cache headers if you want to control caching behavior.

What are Route Handlers?

Route handlers, introduced with the App Router, are located in the app directory. They are defined in files named route.js or route.ts. Unlike API routes, route handlers use the Web Fetch API, which means they handle requests with standard Request and Response objects.

Route handlers can run on various runtimes, including Node.js and Edge functions. This flexibility allows for better performance, especially for low-latency endpoints. Additionally, route handlers support static caching for GET requests, which can be controlled using exports like revalidate and runtime.

Key Differences

Here’s a quick comparison of the two:

Feature	API Routes	Route Handlers
File Location	pages/api/slug.ts	app/api/slug/route.ts
Request Type	NextApiRequest	Request (Web Fetch)
Response Type	NextApiResponse	Response (Web Fetch)
Runtime Environment	Node.js only	Node.js and Edge functions
Caching Behavior	No static caching; manual headers	Supports static caching for GET

When to Use Each

Use API Routes When:

• You need server-side endpoints that always run on Node.js.
• You don’t require static caching.
• You want to handle requests that should not be cached, like internal tools.

Use Route Handlers When:

• You are starting a new Next.js project with the App Router.
• You need edge runtime for faster responses.
• You want to leverage static caching for API responses.
• You are building streaming endpoints or colocating form action handlers with their pages.

Example Code

Here’s a quick example of how you might implement an endpoint that returns a list of posts using both methods:

API Route Example

// pages/api/posts.ts
import type { NextApiRequest, NextApiResponse } from 'next';
import { client } from '@/sanity/client';

type Post = { _id: string; title: string; slug: string };

export default async function handler(req: NextApiRequest, res: NextApiResponse<Post[]>) {
    if (req.method !== 'GET') {
        res.status(405).end();
        return;
    }

    const posts = await client.fetch<Post[]>(`*[_type == "post"]{ _id, title, "slug": slug.current }`);
    res.setHeader('Cache-Control', 's-maxage=60, stale-while-revalidate=300');
    res.status(200).json(posts);
}

Route Handler Example

// app/api/posts/route.ts
import { NextResponse } from 'next/server';
import { client } from '@/sanity/client';

export const revalidate = 60; // ISR: revalidate every 60 seconds

type Post = { _id: string; title: string; slug: string };

export async function GET() {
    const posts = await client.fetch<Post[]>(`*[_type == "post"]{ _id, title, "slug": slug.current }`, {}, { next: { revalidate: 60 }});
    return NextResponse.json(posts);
}

Conclusion

Choosing between Next.js API routes and route handlers depends on your project needs. Understanding their differences helps you optimize performance and manage caching effectively.

Merits

• API Routes: Simple to use, suitable for low-traffic internal tools, no surprises with caching.
• Route Handlers: Support for Edge functions, better caching control, and shorter code for common tasks.

Demerits

• API Routes: Lack of caching support can lead to performance issues, especially under load.
• Route Handlers: More complex mental model and might require learning new patterns for existing developers.

Caution

This article is for educational purposes. Be sure to replace any placeholder values with real ones in your projects. Always verify claims against the original source before relying on them.

Frequently asked questions

• What are Next.js API routes? — They are server-side endpoints located in the pages/api directory, using Node.js.
• What are route handlers in Next.js? — They are server-side endpoints in the app directory, using the Web Fetch API.
• When should I use API routes? — Use them for simple, Node.js-only server-side functionality without caching needs.
• When should I use route handlers? — Use them for new projects needing Edge functions and caching capabilities.
• Can I use both API routes and route handlers in the same project? — Yes, they can coexist during migration.
• How do caching mechanisms differ between the two? — API routes require manual cache headers, while route handlers support static caching automatically.

Tags

#nextjs #approuter #webdevelopment #caching #performance #programming #javascript #webdev