There are so many jobs listed for developers familiar with the Paypal API on GetAFreelancer that the site has a category dedicated to it. And that's not all--there are over 300 API-related listings on the site, which connects freelancers with people who need programmers and designers.
Listrak is an email marketing company solely focused on the ecommerce channel. By getting to know their clients in depth, reviewing clickstream data and transactional history, and plotting customers on a lifecycle grid, Listrak is focused on delivering two things, according to CEO Ross Kramer, "help our customers acquire more new customers, and sell more to existing customers." The Listrak SOAP API makes automation of managing email campaigns easier.
Last year, Facebook announced that it would launch a set of business-centric tools around WhatsApp. The company has also long stated that it would eventually monetize its various messaging platforms. Facebook has taken a step towards both goals with the introduction of the WhatsApp Business API.