API Helper to be used during API requests. Should be used as a must-use plugin in WordPress.

api-helper.php

<?php
/**
 * Plugin Name:  TGM API Helper
 * Plugin URI:   https://thomasgriffin.io
 * Description:  Whitelists the plugins to be loaded during API requests to reduce overhead.
 * Author:       Thomas Griffin
 * Author URI:   https://thomasgriffin.io
 * Version:      1.0.0
 */

// Make sure we can target a valid URI endpoint.
if ( ! isset( $_SERVER['REQUEST_URI'] ) ) {
    return;
}

// Make sure that the endpoint being requested matches a valid API endpoint.
if ( strpos( stripslashes( $_SERVER['REQUEST_URI'] ), '/api/v1/' ) === false ) {
    return;
}

// Define a constant that we can make use of in any API plugins we create.
define( 'TGM_API_REQUEST', true );

// Now that we know this is an API request, let's filter available plugins.
add_filter( 'pre_option_active_plugins', 'tgm_whitelist_active_plugins' );
/**
 * Filters the plugins that should be loaded during this request to reduce overhead.
 *
 * since 1.0.0
 *
 * @param array $plugins   The active plugins to be loaded in the request.
 * @retun array $whitelist Whitelisted plugins that should only be loaded during the request.
 */
function tgm_whitelist_active_plugins( $plugins ) {

    // This is my base API plugin to handle all API routes. I want this loaded before everything else.
    $whitelist = array(
        'api-routes/api-routes.php'
    );

    // You can easily conditionally load plugins based on the URI path. Here is an example for an API endpoint called "update".
    if ( strpos( stripslashes( $_SERVER['REQUEST_URI'] ), '/api/v1/update/' ) !== false ) {
        $whitelist[] = 'api-update-helper/api-update-helper.php';
    }

    // Finally, we can load any API plugin that depends on all the others last.
    $whitelist[] = 'api-depends/api-depends.php';

    // Return the whitelist instead of the default plugins.
    return $whitelist;

}