At masterclass Solutions we are well-versed with application program interfaces (APIs), a tool that make it possible to manage software applications. While invisible to end users, APIs are essential for communication between programs. Social media networking giants Facebook and Twitter are just a couple of companies that have made good use of open or public APIs. Basically, an open API is one in which an organization publishes its software to be shared freely. A startup, for example, may want to open its API, as doing so encourages third parties to use its software.