What is an API?
API stands for Application Programming Interface. In simpler words, APIs are stand-alone pieces of software that we send calls to and get the yield. Most developers deal with APIs every day. If you website uses login using Facebook, that is connected to Facebook API, if you save your files in Dropbox, that is an API and so on. As the importance of API development grows, we also realize that being able to test these APIs properly is a crucial task. With APIs, applications talk to each other without any user knowledge or intervention.
What is API Testing?
This is type of functional testing in which developer can test APIs. API testing is entirely different from GUI testing and mainly concentrates on the business logic layer of the software architecture. API testing uses software to send calls to the API and get the output. This (figure 1) represent the OSI model of API.