WordPress REST API to Manage ACF Custom Fields

Nov 04, 2025 |

8 minutes read

Unlocking the Power of WordPress REST API to Manage ACF Custom Fields

While originally designed as a blogging engine, WordPress has matured into a fullfledged content management system (CMS) capable of powering complex web projects and applications. One of the key enhancements in this evolution is the plugin Advanced Custom Fields (ACF), which empowers developers and content teams alike to define bespoke fields beyond the builtin post title, body, and excerpt. When paired with the WordPress REST API, ACF transforms WordPress into a true headless backend or a flexible data platform for contentdriven apps. For any WordPress website developer, mastering this integration is essential to building modern, scalable, and API-ready websites.

Understanding ACF Custom Fields

Advanced Custom Fields enables you to attach structured fields to posts, pages, users, customposttypes, taxonomies, or even global option pages. These fields span from the simple (text, number, true/false) to the complex, such as repeater fields, flexible content layouts, galleries, and more. In a realestate site, for example, you might define fields like “price”, “square footage”, “number of bedrooms”, or “list of amenities” — pieces of data that wouldn’t fit into the standard WordPress post schema.

By modeling data in this structured way:

– Editors have a consistent interface for entering values.
– Developers can predict and consume structured data.
– The site architecture remains clearer, datadriven, and easier to integrate with external systems.

The Role of the WordPress REST API

The WordPress REST API provides a standardized HTTPbased interface for interacting with WordPress content. Using endpoints like `/wp-json/wp/v2/posts`, `/wp-json/wp/v2/users`, or customposttype endpoints, you can fetch, create, update, and delete content programmatically. Combine that with ACF, and suddenly all those custom fields become firstclass participants in your API-driven workflows.

Accessing ACF Fields via the REST API

Out of the box, ACF’s field groups are not exposed via the REST API until you opt them in. Within ACF’s settings, under each field group you’ll find a “Show in REST API” toggle. Enable that and WordPress will include an acf object in the JSON response.

Example Response:


{
  "id": 101,
  "title": "WordPress REST API and ACF",
  "acf": {
    "subtitle": "Mastering custom fields via API"
  }
}

Updating ACF Fields via REST API

To update an ACF field, send a PUT or POST request with authentication to the endpoint `/wp-json/wp/v2/posts/{id}` with the following payload:


{
  "acf": {
    "subtitle": "Updated subtitle via REST API"
  }
}

Creating Posts with ACF Fields

You can create new posts (or custom post types) and include ACF fields in the same request:


{
  "title": "Luxury Apartment in NYC",
  "status": "publish",
  "acf": {
    "price": "950000",
    "location": "New York, NY"
  }
}

Real-World Use Cases

– Ecommerce / product enrichment: Store extra product data such as warranty information or size charts.
– Realestate platforms: Manage detailed property data accessible via an API.
– Headless WordPress: Use WP as a backend for React or Vue apps.
– Automated workflows & integrations: Sync with CRMs, analytics platforms, or trigger updates externally.

Best Practices

Authenticate & Authorize API Requests: Use secure authentication methods.
Enable Only Needed Fields: Avoid exposing unnecessary fields.
Plan Field Organization: Keep logical grouping for predictable responses.
Watch Performance: Cache large payloads and limit nested fields.
Use Return Formats Wisely: Choose URL or array for media fields.
Secure Output: Escape HTML content properly.
Use HTTPS: Always serve API requests over secure connections.

Example Workflow

1. Create ACF field groups in WordPress.
2. Enable “Show in REST API.”
3. Send GET requests to verify ACF data.
4. Use PUT or POST to update/create posts.
5. Consume the data in React, Vue, or mobile apps.

Why This Matters

By combining WordPress, ACF, and the REST API, you can build dynamic, scalable, and datadriven systems. This architecture enables headless CMS setups, modern frontend integrations, and robust data workflows.

Unlock the True Potential of WordPress with ACF & REST API

The Way Forward

Mastering ACF and REST API integration modernizes how you use WordPress. With secure configuration, performance optimization, and thoughtful design, you can transform WordPress into a versatile, APIdriven content hub suitable for almost any application.

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Mayur Dosi

Nov 04 2025

I am Assistant Project Manager at iFlair, specializing in PHP, Laravel, CodeIgniter, Symphony, JavaScript, JS frameworks ,Python, and DevOps. With extensive experience in web development and cloud infrastructure, I play a key role in managing and delivering high-quality software solutions. I am Passionate about technology, automation, and scalable architectures, I am ensures seamless project execution, bridging the gap between development and operations. I am adept at leading teams, optimizing workflows, and integrating cutting-edge solutions to enhance performance and efficiency. Project planning and good strategy to manage projects tasks and deliver to clients on time. Easy to adopt new technologies learn and work on it as per the new requirments and trends. When not immersed in code and project planning, I am enjoy exploring the latest advancements in AI, cloud computing, and open-source technologies.