Buying Integration Guide
The eBay Buy APIs (Marketing, Browse, Feed, and Order), along with the Commerce Taxonomy API, provide the capabilities you need to create an off-eBay shopping experience that lets your users find and buy items listed on eBay. These are RESTful APIs that use OAuth authentication, JSON payloads, and eBay HTTP headers.
You can use the eBay Buy APIs to build an application that displays eBay items, lets shoppers purchase their items, and lets you obtain details about specific purchase orders. Shoppers can be guests or eBay members. With guest shoppers, the buyer is anonymous and you must provide all their information. With eBay members, the buyer is signed into eBay.
You can use the Taxonomy API to make the Browse API Search for Items call more effective, by narrowing the search focus to categories in buyers' areas of interest. You will want to use the Taxonomy API to identify all of the categories that cover the items your buyers might want to purchase, while minimizing the number of unwanted items that might clutter up the listings. See Finding Categories for Buy API Calls.
Important! The eBay Buy APIs are available as a public beta release. Accordingly, there may be some limitations and conditions on their use. For more information, refer to API launch stages in the Using eBay RESTful APIs guide.