If you need only json:api: Buy only Json:API and buy authentication module separate as per your need. Base API module will be integrated well.
If you need only GraphQL: Buy only GraphQL and buy authentication module separate as per your need. Base API module will be integrated well.
Budget saver light version: We tried to cover most used API tools in one light version here. If you are not happy with light version you can buy remaining modules later too. So in case if you are not sure what to buy discuss with us or go with light version in 75% cases light version is enough to make your odoo powerful with API.