Overriding home_url() and site_url() for headless WordPress setups on Pressable

If you’re using WordPress in a headless setup (where the WordPress backend powers a decoupled frontend hosted elsewhere), you may want WordPress to return your frontend URL when generating links via home_url() or site_url().

However, defining WP_HOME and WP_SITEURL in wp-config.php doesn’t always produce the expected result on Pressable.

Why overriding WP_HOME doesn’t work on Pressable

At Pressable, our platform may define WP_HOME and WP_SITEURL before WordPress fully loads. This means attempts to override these constants later in wp-config.php have no effect.

Fortunately, WordPress uses the home and siteurl options internally when calling functions like home_url() and get_home_url(). These option values can be filtered at runtime, which gives us a clean workaround.

The solution: use a must-use plugin to override URLs

A must-use (mu) plugin is a type of plugin that loads automatically and cannot be disabled via the WordPress admin. It’s ideal for critical runtime overrides like this.

To force WordPress to return your frontend URL:

1. Connect to your site’s file system (via SSH, SFTP or a file manager plugin)
2. Create a file in /wp-content/mu-plugins/ named something like override-home-url.php
3. Add the following code to that file, replacing the example URL with your actual frontend domain:

<?php
// /wp-content/mu-plugins/override-home-url.php

add_filter('option_home', function() {
    return 'https://your-frontend-domain.com';
});

add_filter('option_siteurl', function() {
    return 'https://your-frontend-domain.com';
});

add_filter('home_url', function($url, $path = '', $orig_scheme = null, $blog_id = null) {
    return rtrim('https://your-frontend-domain.com', '/') . $path;
}, 10, 4);

NOTE: Remember to replace https://your-frontend-domain.com with the actual front-end domain for your web app.

When should you use this approach?

This override is appropriate only if:

• You’re running WordPress in a headless configuration
• You need WordPress to return a different frontend URL for output functions like home_url() or site_url()
• You’re not relying on WP_HOME/WP_SITEURL constants to enforce the site’s primary URL

Do not use this method on traditional WordPress setups—it will result in unexpected behavior or broken links.