Register a Custom REST API Endpoint in WordPress

Register a custom REST API endpoint to expose data from your theme or plugin. For more on securing the REST API.

add_action( 'rest_api_init', function () {
    register_rest_route( 'savvy/v1', '/recent-posts/', array(
        'methods'             => 'GET',
        'callback'            => 'savvy_get_recent_posts',
        'permission_callback' => '__return_true',
    ) );
} );

function savvy_get_recent_posts() {
    $posts = get_posts( array(
        'numberposts' => 5,
        'post_status' => 'publish',
    ) );

    $data = array();
    foreach ( $posts as $post ) {
        $data[] = array(
            'id'    => $post->ID,
            'title' => $post->post_title,
            'link'  => get_permalink( $post ),
        );
    }

    return rest_ensure_response( $data );
}

Add to functions.php. Access at /wp-json/savvy/v1/recent-posts/. Set permission_callback to restrict access if needed.