Centra has a few different API's for different things. Below is an explanation about the different API's and when to use them.
Each API has its own plugin. Some of the API's needs activation from Centra, such as the Subscription API, but the other ones can be enabled easily by just adding a new plugin to your store.
To enable a plugin by going to 'System', then select 'Stores' in the main menu to the left. Select what store you want your API to connect to and select the API in the list of plugins after clicking '+Add plugin method'. You will need administration rights in Centra to have access to the 'System'.
Click on each link to read more about each API
Checkout API - This is our hybrid webshop API, able to operate both in Client and Server mode, giving you access to products catalog, prices, payments, checkout, shipping options, vouchers, anything you need to build a webshop.
Shop API - Shop API is an older, soon to be deprecated webshop API, which only works in authenticated Server mode. It operates directly on selections (instead of sessions), is not aware of the end-user context, and is less capable performance-wise, since it doesn't use ES cache internally, like Checkout API does.
Subscription API - The Subscription API is used for recurring sales where the orders are created automatically using a specified subscription period. Using the API you are able to create new subscriptions that will authorize the payment provider and enable orders to be created.
Order API - The Order API is mostly used for pick & pack services to finalize already placed orders. It can create and fetch supplier orders. It supports inserting regular orders directly without working with an open cart, which means the order was settled outside of Centra.
Integration API (GraphQL) - GraphQL is the future of API technology, we believe. This API gives you granular access to almost all parts of Centra, including the parts previously available only from the backend UI. Currently, this Integration API works mostly in read-only mode, but we are adding new functionalities (including write) with every Centra version. Once fully developed, it will deprecate Order API.