WordPress has good rest api but its havy , By this plugin you can receive faster response than default WP rest api and you can simply add new extra field to response items
Call like this http://x.com/wp-json/get_menu/mainmenu or /wp-json/get_post/posts or wp-json/get_post/posts?categories=1 or wp-json/get_post/posts?categories=1&per_page=1&page=2