An Intro to APIs for Mobile Apps API is an acronym for “application program interface.” It’s a technical development environment that enables access to another party’s application or platform. The most famous, and most often used by mobile developers, is Facebook’s API. It allows mobile developers limited access to the profile identity of Facebook members to verify identification on login. It enables Facebook members to sign up for a third-party app like Rdio or Candy Crush using their Facebook account. Facebook’s API also allows its own users to post content to their News Feed from third-party mobile applications they’re using. This function has enabled many apps to grow their user base very quickly. Like Facebook, Twitter has an API that can also be used by third-party mobile developers to identify their users on sign up and to enable users to post content easily from an app to their Twitter account. If you’re building an application that will leverage sharing to Twitter or Facebook on your app’s behalf, be aware that spamming, direct competition and other actions can lead to revoked access for these APIs. LinkedIn’s API is another popular interface. Because LinkedIn is a networking site for business professionals, a user’s LinkedIn network, or social graph, is likely to be different from their Facebook or Twitter networks. As a result, LinkedIn’s API is best reserved for business applications—with notable partners like Evernote, which leverages LinkedIn’s API to enable users to scan business cards in Evernote, then directly connect with that user’s LinkedIn profile. In 2015, LinkedIn announced that it was limiting its third-party API access to official partnerships, with its remaining open APIs available for only a handful of uses like content sharing, use of a profile as an identity, and certification posting. If you’re looking for more access to LinkedIn’s APIs, you’ll need to sign up for the partnership program. Google Maps provides a hugely popular API that enables mapping and location services in third-party applications. Unlike social APIs, Google charges for its API if there’s a fee for your application, or if you exceed 100,000 queries of their API in a 24-hour period, but paying for a Work license allows for more query capacity. If mapping is central to your mobile application, you’ll probably need to pay Google for access to their API. Here are a few other popular APIs to know about: YouTube: provides access to their rich repository of video content AccuWeather: offers access to weather information, which is very popular on mobile Flickr: enables access to a large library of photography Apple’s iOS 8 operating system enabled better and easier sharing of content between third-party applications. The operating system itself provided an alternative to using the APIs of Facebook or Twitter, allowing users to share content easily from an app to their Facebook and Twitter accounts. The change didn’t enable identification on sign up, but made it much easier—and much cheaper—for your developer to integrate into your application than using the APIs produced by Facebook and Twitter. In short, APIs enable apps to interact with each other. They can enhance the user experience and might even help fuel the popularity of your app. Find a freelance API developer to start putting them to work for you.