How to Set Up WordPress as a Headless CMS with the REST API and Next.js

ByAkensai

Learning how to set up WordPress as a headless CMS with the REST API and Next.js gives you the best of both worlds. You get WordPress’s powerful content management on the backend and Next.js’s blazing-fast rendering on the frontend. This architecture decouples your content layer from your presentation layer. The result is a faster, more flexible web application. In this tutorial, you’ll configure WordPress to serve content through its built-in REST API. Then you’ll build a Next.js frontend that fetches and displays that content. This approach is popular with developers who want modern JavaScript tooling without abandoning WordPress’s familiar editing experience. By the end, you’ll have a working headless setup running locally that you can deploy to production.

Prerequisites for How to Set Up WordPress as a Headless CMS with the REST API and Next.js

Before you start, make sure you have the following in place.

Required software:
– WordPress installed and running (local or remote server)
– Node.js version 18 or higher
– npm or yarn package manager
– A code editor like VS Code
– Basic terminal/command line access

Assumed knowledge:
– You’re comfortable with WordPress administration
– You understand basic JavaScript and React concepts
– You can run commands in a Linux or macOS terminal

Estimated time: 45–60 minutes

You should have a WordPress site with at least a few published posts. The WordPress REST API is enabled by default on all installations running version 4.7 or higher. You don’t need any extra plugins to get started. Check your WordPress version in your admin dashboard under Dashboard → Updates.

Read the official WordPress REST API documentation if you want a deeper understanding of available endpoints before you begin.

Step-by-Step Guide to How to Set Up WordPress as a Headless CMS with the REST API and Next.js

This event shares similarities with: How to Set Up Nginx as a Reverse Proxy with Ssl on Ubuntu Server

Step 1: Verify your WordPress REST API is working

Open your browser and visit:

https://yourdomain.com/wp-json/wp/v2/posts

You should see a JSON response with your published posts. If you get an empty array, make sure you have published posts. If you get a 404 error, go to Settings → Permalinks in WordPress and click Save Changes. This flushes the rewrite rules.

Step 2: Enable CORS on your WordPress server

Your Next.js app runs on a different port or domain. WordPress needs to allow cross-origin requests. Add the following code to your theme’s functions.php file or a custom plugin:

add_action('rest_api_init', function() {
    remove_filter('rest_pre_serve_request', 'rest_send_cors_headers');
    add_filter('rest_pre_serve_request', function($value) {
        header('Access-Control-Allow-Origin: http://localhost:3000');
        header('Access-Control-Allow-Methods: GET, POST, OPTIONS');
        header('Access-Control-Allow-Credentials: true');
        return $value;
    });
}, 15);

Replace http://localhost:3000 with your actual Next.js domain in production.

Step 3: Create a new Next.js project

Open your terminal and run the following commands:

npx create-next-app@latest my-headless-blog
cd my-headless-blog

When prompted, choose Yes for TypeScript if you prefer it. Select App Router when asked. This tutorial uses the App Router structure available in Next.js 13 and above.

Step 4: Set up your environment variable

Create a .env.local file in your project root:

NEXT_PUBLIC_WORDPRESS_API_URL=https://yourdomain.com/wp-json/wp/v2

Never hardcode your WordPress URL directly into components. Using an environment variable makes switching between development and production much easier.

Step 5: Create a WordPress API utility file

Inside your project, create the file lib/wordpress.js:

const API_URL = process.env.NEXT_PUBLIC_WORDPRESS_API_URL;

export async function getPosts() {
    const res = await fetch(`${API_URL}/posts?_embed&per_page=10`);
    if (!res.ok) {
        throw new Error('Failed to fetch posts');
    }
    return res.json();
}

export async function getPostBySlug(slug) {
    const res = await fetch(`${API_URL}/posts?slug=${slug}&_embed`);
    if (!res.ok) {
        throw new Error('Failed to fetch post');
    }
    const posts = await res.json();
    return posts[0];
}

The _embed parameter tells WordPress to include featured images and author data in the response. This saves you extra API calls.

Step 6: Build the blog index page

Open app/page.js and replace its contents with:

import { getPosts } from '@/lib/wordpress';
import Link from 'next/link';

export default async function Home() {
    const posts = await getPosts();

    return (
        <main>
            <h1>My Headless Blog</h1>
            <ul>
                {posts.map((post) => (
                    <li key={post.id}>
                        <Link href={`/posts/${post.slug}`}>
                            {post.title.rendered}
                        </Link>
                    </li>
                ))}
            </ul>
        </main>
    );
}

Step 7: Create the single post page

Create the file app/posts/[slug]/page.js:

import { getPostBySlug } from '@/lib/wordpress';

export default async function PostPage({ params }) {
    const post = await getPostBySlug(params.slug);

    return (
        <article>
            <h1 dangerouslySetInnerHTML={{ __html: post.title.rendered }} />
            <div dangerouslySetInnerHTML={{ __html: post.content.rendered }} />
        </article>
    );
}

Step 8: Run your Next.js development server

npm run dev

Visit http://localhost:3000 in your browser. You should see your WordPress posts listed on the homepage. Click any post to view its full content.

Troubleshooting Common Issues When Setting Up WordPress as a Headless CMS

Problem: Blank page or no posts showing
Check that your NEXT_PUBLIC_WORDPRESS_API_URL is correct in .env.local. Restart the dev server after changing environment variables.

Problem: CORS errors in the browser console
Double-check the CORS code in your functions.php. Make sure the origin URL matches exactly, including the port number. Some hosting providers block custom headers. Contact your host if the issue persists.

Problem: 404 on the REST API endpoint
Go to WordPress Settings → Permalinks and click Save Changes. This rebuilds the rewrite rules and usually fixes REST API 404 errors.

Problem: Featured images not loading
Make sure you’re using the _embed parameter in your fetch calls. Access the image URL with post._embedded['wp:featuredmedia'][0].source_url.

Problem: HTML entities showing in titles
WordPress returns encoded HTML in titles. Use dangerouslySetInnerHTML or a library like he to decode them properly.

Read the Next.js data fetching documentation for advanced caching and revalidation strategies.

Conclusion

You now know how to set up WordPress as a headless CMS with the REST API and Next.js. You’ve configured CORS on your WordPress server, created a utility library to fetch posts, and built a working Next.js frontend that displays your content dynamically. This setup gives your site excellent performance because Next.js handles rendering on the edge or server. Your content editors still get the familiar WordPress dashboard they know. From here, you can add categories, tags, custom post types, and even authentication for protected content. You can also explore static generation with generateStaticParams to pre-render posts at build time for even faster load speeds. This headless architecture scales well for blogs, marketing sites, and content-heavy applications alike.

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