Many organizations provide external — albeit sometimes limited — APIs and documentation that allow individuals and companies outside of that organization to develop applications using its services. Depending on the external API, there may be registration, payment, or other limitations involved. For example, The New York Times provides an extensive external API that is free but requires that developers register and follow certain guidelines.
Google Maps also provides APIs that allow developers to embed maps in their websites and applications, as well as access directions and estimated travel times. Lyft, for example, uses Google Maps’ API. Other popular external APIs include Yelp’s Business APIs, which enables the user to find businesses, the OpenWeatherMap API, which retrieves weather data, and the Microsoft Azure Emotion API, which determines emotions in images.
Using external APIs allows developers to create their own mashup applications, like one that uses the Yelp Business API to find top-rated coffee shops in a neighborhood and display them on user interfaces as a map with custom icons via the Google Maps API.