The official eBay Java library can be found on the eBay SDK site, where resources include attributes, calls, and classes. This library helps to work with the SDK having the eBay Trading API in mind. Additional tools cover installation, authorization, and program application. eBay uses Eclipse open source software.
Square is moving beyond the retail terminal thanks to a handful of new APIs meant to help companies accept payments in more places. The E-Commerce API and Register API target retailers large and small with a simple set of tools that integrate fully with Square's payment processing platform.