Here is a list of some popular APIs:
- Google Maps: Well supported for Android and Web, some support for iOS.
- Facebook: app login features, update status, etc.
- Paypal: Used for in-app purchases.
- Stripe: New alternative to Paypal.
- Watson: Artificial Intelligence, such as personality and tone predicting, text to speech, analytics, and more.
- Google Analytics: free version gives basic, easy to use analytics. Includes an enterpise version for better insights.
For most APIs, you will have to sign up for an account to get an API key, which lets you access the API (called an API call). Some companies also ask you to download a Software Development Kit, or SDK, to install the API data.
Also, since APIs need access to a company's server, almost every API requires an internet connection.
In addition to APIs, developers can also use tools called Libraries or Packages to add functionality to their apps that is not part of an app software's default components. Unlike APIs, libraries do not usually need an internet connection and are often open source (free).
Here are some popular frameworks and libraries:
- Lottie: includes animations to give your app a polished look.
- Horizontal Calendar: a different type of calendar view for Android.
- PDTSCalendarView: improves the calendar view for iOS.
- TextFieldEffects: adds polished animations for text field interaction (iOS).
- iRate: library for asking users to rate your app.
- AmCharts: libraries for anything graphing related. Great for any type of analytics page or platform.
- Proxitee: iOS tools for implementing geofencing and iBeacons inside an app.