Mock sample for your project: Jumpseller API

A product library is a representation of all the items that can be
displayed, put in a shopping cart and sold to a customer. Items may be
either producs or discounts.
A product is a synthetic construct, wrapping one or more variants (which is
the actual item being sold) Variants expresses different variations of
properties such as for example price, size or color. A discount will reduce
the total amount charged in a shopping cart. It can be used per item line,
or on the whole cart. It may reduce the affected amount by a percentage, or
by a fixed amount.
Together, the above types of entities makes up a complete library. The
library can be fetched as a whole through the library endpoint, where each
consecutive change applied to the library is available. Once the full
library is retrieved, only later events needs to be fetched to keep the
client up to date with the server
All path patterns "/organizations/{organizationUuid}/" can be replaced
with "/organizations/self/" for convenience as all endpoints are for
authorized users.

Documentation of the Billbee REST API to connect a Billbee account to external aplications.
Endpoint
The Billbee API endpoint base url is https://app.billbee.io/api/v1
Activation
You have to enable the API in the settings of your Billbee account. In addition you need a Billbee API Key identifying the application you develop. To get an API key, send a mail to [email protected] and send us a short note about what you are building.
Authorization & security
Because you can access private data with the Billbee API, every request has to be sent over https and must
Contain a valid API Key identifying the application/developer. It has to be sent as the HTTP header X-Billbee-Api-Key
Contain a valid user login with billbee username and api password in form of a basic auth HTTP header
Throttling
Each endpoint has a throttle of max 2 requests per second per combination of API Key and Billbee user.
When you exceed these 2 calls, the API will return a HTTP 429 status code

Service for providing information to sellers about their listings being non-compliant, or at risk for becoming non-compliant, against eBay listing policies.

One API serving data spanned across multiple verticals

The Account API gives sellers the ability to configure their eBay seller accounts, including the seller's policies (the Fulfillment Policy, Payment Policy, and Return Policy), opt in and out of eBay seller programs, configure sales tax tables, and get account information. For details on the availability of the methods in this API, see Account API requirements and restrictions.

The price is a fundamental building block for your listing on Walmart.com. You can use the price management APIs to set up and manage the price for a given item

Note: This is a (Limited Release) API available only to select developers approved by business units. Retrieves the authenticated user's account profile information. It can be used to let users log into your app or site using eBay, which frees you from needing to store and protect user's PII (Personal Identifiable Information) data.

dropX.io API provides programmatic access to the e-commerce intelligence data.

Use the Taxonomy API to discover the most appropriate eBay categories under which sellers can offer inventory items for sale, and the most likely categories under which buyers can browse or search for items to purchase. In addition, the Taxonomy API provides metadata about the required and recommended category aspects to include in listings, and also has two operations to retrieve parts compatibility information.

Polls is a simple API allowing consumers to view polls and vote in them.

Service for providing information to sellers about their listings being non-compliant, or at risk for becoming non-compliant, against eBay listing policies.