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SEO Machine publishes content directly to WordPress using the REST API with full Yoast SEO metadata support. This integration enables automated publishing while maintaining complete control over SEO fields.

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Prerequisites

  • WordPress site with REST API enabled (default in WP 4.7+)
  • Yoast SEO plugin installed and activated
  • User account with edit_posts capability
  • Application Password or Basic Auth credentials

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Installation Methods

Choose one of the following installation methods. Both accomplish the same goal: exposing Yoast SEO fields via the REST API. Must-Use (MU) plugins are automatically activated and cannot be accidentally deactivated, making them ideal for critical functionality.
1

Upload the plugin file

Upload seo-machine-yoast-rest.php from the wordpress/ directory to:
wp-content/mu-plugins/seo-machine-yoast-rest.php
Create the mu-plugins folder if it doesn’t exist in your wp-content directory.
2

Verify activation

MU-plugins are automatically activated. No additional steps required.Verify the plugin is active by checking:
  • Navigate to Plugins → Must-Use in WordPress admin
  • You should see “SEO Machine - Yoast REST API Support” listed
Advantages:
  • Survives theme updates and changes
  • Cannot be accidentally deactivated
  • Clean separation from theme code
  • Ideal for production environments

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Option B: Functions.php Snippet

Add the code directly to your theme’s functions.php file or use a code snippets plugin.
1

Copy the code

Copy the contents of functions-snippet.php from the wordpress/ directory.
2

Add to your site

Choose one method:Method 1: Child Theme (Recommended)Paste the code at the end of your child theme’s functions.php:
wp-content/themes/your-child-theme/functions.php
Method 2: Code Snippets PluginInstall a code snippets plugin like WPCode or Code Snippets:
  1. Create a new snippet
  2. Paste the code
  3. Set to run everywhere
  4. Activate the snippet
Advantages:
  • No new files to manage
  • Works well with code snippet plugins
  • Easy to modify for custom requirements
Disadvantages:
  • Lost if theme is changed/updated (unless using child theme)
  • Can be accidentally deactivated (if using snippets plugin)

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Plugin Code

The MU-plugin registers custom REST API fields for Yoast SEO metadata: 
add_action('rest_api_init', function() {
    // Only proceed if Yoast SEO is active
    if (!defined('WPSEO_VERSION')) {
        return;
    }

    register_rest_field('post', 'yoast_seo', [
        'get_callback' => function($post) {
            return [
                'focus_keyphrase' => get_post_meta($post['id'], '_yoast_wpseo_focuskw', true),
                'seo_title' => get_post_meta($post['id'], '_yoast_wpseo_title', true),
                'meta_description' => get_post_meta($post['id'], '_yoast_wpseo_metadesc', true),
            ];
        },
        'update_callback' => function($value, $post) {
            if (!current_user_can('edit_post', $post->ID)) {
                return new WP_Error('rest_forbidden', 'Permission denied.', ['status' => 403]);
            }

            if (isset($value['focus_keyphrase'])) {
                update_post_meta($post->ID, '_yoast_wpseo_focuskw', sanitize_text_field($value['focus_keyphrase']));
            }
            if (isset($value['seo_title'])) {
                update_post_meta($post->ID, '_yoast_wpseo_title', sanitize_text_field($value['seo_title']));
            }
            if (isset($value['meta_description'])) {
                update_post_meta($post->ID, '_yoast_wpseo_metadesc', sanitize_text_field($value['meta_description']));
            }

            return true;
        },
    ]);
});

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WordPress Configuration

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Create Application Password

1

Navigate to user profile

In WordPress admin, go to Users → Profile (or Users → All Users and edit your user).
2

Generate application password

Scroll to the Application Passwords section at the bottom.
  1. Enter a name: SEO Machine
  2. Click Add New Application Password
  3. Copy the generated password immediately (it’s only shown once)
3

Save credentials

Store the username and application password securely. You’ll need these for the SEO Machine configuration.
Application passwords are only shown once. If you lose it, you’ll need to revoke and create a new one.

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Configure SEO Machine

Add your WordPress credentials to data_sources/config/.env: 
# WordPress Configuration
WP_SITE_URL=https://yourdomain.com
WP_USERNAME=your_username
WP_APP_PASSWORD=xxxx xxxx xxxx xxxx xxxx xxxx
The application password includes spaces - keep them in the configuration.

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API Usage

Once configured, SEO Machine can publish posts with Yoast SEO metadata using the WordPress REST API.

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Example: Create Post with SEO Metadata

curl -X POST https://yourdomain.com/wp-json/wp/v2/posts \
  -u "username:xxxx xxxx xxxx xxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "title": "How to Start a Podcast in 2026",
    "content": "<p>Your article content here...</p>",
    "status": "draft",
    "yoast_seo": {
      "focus_keyphrase": "start a podcast",
      "seo_title": "How to Start a Podcast: Complete 2026 Guide",
      "meta_description": "Learn how to start a podcast with our step-by-step guide. Equipment, hosting, editing, and promotion strategies for beginners."
    }
  }'

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Example: Update Existing Post

curl -X POST https://yourdomain.com/wp-json/wp/v2/posts/123 \
  -u "username:xxxx xxxx xxxx xxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "yoast_seo": {
      "focus_keyphrase": "podcast monetization",
      "seo_title": "Podcast Monetization: 12 Ways to Make Money",
      "meta_description": "Discover 12 proven podcast monetization strategies including sponsorships, memberships, and affiliate marketing."
    }
  }'

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Using the Publish Command

SEO Machine provides a built-in command for publishing: 
/publish-draft drafts/podcast-guide.md
This automatically:
  1. Converts Markdown to WordPress blocks
  2. Uploads images to WordPress media library
  3. Sets Yoast SEO metadata (focus keyphrase, SEO title, meta description)
  4. Creates the post as a draft for review
  5. Returns the post URL and edit link

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Metadata Mapping

SEO Machine maps its internal metadata to Yoast SEO fields:
SEO Machine FieldYoast SEO FieldWordPress Meta Key
Focus KeyphraseFocus Keyphrase_yoast_wpseo_focuskw
SEO TitleSEO Title_yoast_wpseo_title
Meta DescriptionMeta Description_yoast_wpseo_metadesc

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Security

The integration includes multiple security measures:
  • Requires valid WordPress credentials (application password or basic auth)
  • All requests must include authentication headers
  • Failed authentication returns 401 Unauthorized
  • User must have edit_posts capability
  • Updating existing posts requires edit_post permission for that specific post
  • Insufficient permissions return 403 Forbidden
  • All inputs sanitized with sanitize_text_field()
  • HTML tags stripped from metadata fields
  • XSS protection built-in
  • Plugin only registers fields if Yoast SEO is active
  • Gracefully degrades if Yoast is deactivated
  • No errors if Yoast is not installed

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Troubleshooting

Problem: 401 Unauthorized errorSolutions:
  • Verify application password is correct (including spaces)
  • Ensure username is correct
  • Check if Application Passwords feature is enabled (Settings → Permalinks, must not be “Plain”)
  • Try regenerating the application password
Problem: yoast_seo field not available in API responseSolutions:
  • Verify Yoast SEO plugin is installed and activated
  • Check that MU-plugin or functions.php code is active
  • Confirm user has edit_posts capability
  • Test API endpoint: GET /wp-json/wp/v2/posts/123
Problem: 403 Forbidden when updating postsSolutions:
  • Verify user has edit_post capability for the specific post
  • Check user role (Editor or Administrator required)
  • Ensure user owns the post or has sufficient privileges
Problem: Cannot connect to REST APISolutions:
  • Verify permalinks are NOT set to “Plain” (Settings → Permalinks)
  • Check .htaccess file for REST API rewrites
  • Disable security plugins temporarily to test
  • Confirm site URL is correct (https vs http)

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Advanced Configuration

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Custom Post Types

To support custom post types, modify the plugin to register fields for additional post types: 
// Register for custom post type
register_rest_field('your_post_type', 'yoast_seo', [
    // ... same callbacks as above
]);

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Additional Yoast Fields

Extend the integration to include more Yoast SEO fields: 
'get_callback' => function($post) {
    return [
        'focus_keyphrase' => get_post_meta($post['id'], '_yoast_wpseo_focuskw', true),
        'seo_title' => get_post_meta($post['id'], '_yoast_wpseo_title', true),
        'meta_description' => get_post_meta($post['id'], '_yoast_wpseo_metadesc', true),
        'canonical_url' => get_post_meta($post['id'], '_yoast_wpseo_canonical', true),
        'meta_robots_noindex' => get_post_meta($post['id'], '_yoast_wpseo_meta-robots-noindex', true),
        'meta_robots_nofollow' => get_post_meta($post['id'], '_yoast_wpseo_meta-robots-nofollow', true),
    ];
},

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Webhook Notifications

Trigger webhooks when posts are published via SEO Machine: 
add_action('save_post', function($post_id, $post) {
    // Check if published via REST API
    if (defined('REST_REQUEST') && REST_REQUEST) {
        // Trigger webhook
        wp_remote_post('https://your-webhook-url.com', [
            'body' => [
                'post_id' => $post_id,
                'post_title' => $post->post_title,
                'post_url' => get_permalink($post_id),
            ]
        ]);
    }
}, 10, 2);

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Next Steps

Analytics Setup

Configure GA4, Search Console, and DataForSEO to track performance

Publishing Workflow

Learn the complete content creation and publishing workflow

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