Getting Started with Advanced Custom Fields (ACF) in WordPress

Advanced Custom Fields (ACF) is the plugin that turns WordPress from "a blogging platform with some custom fields bolted on" into a genuine flexible CMS. Here's how to go from installing it to displaying custom data on the frontend.

Creating a Field Group

In the WordPress admin, go to Custom Fields → Add New. Add fields (text, image, repeater, relationship, etc.), then set the location rule — e.g., "Post Type is equal to Testimonial" — so this field group only appears where it's relevant.

The Fields Worth Knowing

• Text/Textarea — simple values, e.g. a job title
• Image — returns an array with URL, alt text, and sizes
• Repeater — a list of sub-fields, e.g. multiple "features" on a product
• Relationship — link this post to other posts (e.g., "related products")

Displaying ACF Data in a Template

<?php if (have_rows('features')) : ?>
  <ul>
    <?php while (have_rows('features')) : the_row(); ?>
      <li><?php the_sub_field('feature_name'); ?></li>
    <?php endwhile; ?>
  </ul>
<?php endif; ?>

$image = get_field('hero_image');
if ($image) {
    echo '<img src="' . esc_url($image['url']) . '" alt="' . esc_attr($image['alt']) . '">';
}

Registering Fields in Code (ACF Local JSON)

For any real project, define field groups in PHP or export as local JSON rather than only in the database UI — this makes fields version-controllable and lets them ship with your theme/plugin across environments:

acf_add_local_field_group([
    'key' => 'group_hero',
    'title' => 'Hero Section',
    'fields' => [
        ['key' => 'field_hero_image', 'name' => 'hero_image', 'type' => 'image'],
    ],
    'location' => [[['param' => 'post_type', 'operator' => '==', 'value' => 'page']]],
]);

ACF and the REST API / Gutenberg

By default, ACF field values don't appear in the REST API response automatically. Add show_in_rest when registering fields, or hook into rest_prepare_{post_type} to manually add them — essential if a headless frontend (Next.js, for example) is going to consume this content.

Once ACF clicks, most "can the client edit this themselves" requirements stop meaning custom admin pages and just mean one more field group.