If you're a developer or you've spent time learning about app development, you've undoubtedly heard about the concept of application programming interface or API. There are a lot of different services we use daily to stay connected. We post updates on Facebook, we share images on Instagram and we keep our careers sharp using LinkedIn. All of these services and products share data between them and they're able to ensure sharing through the use of APIs.

So what is exactly an API? Check any app on your phone — it's likely to use Facebook’s API to connect and share data. Facebook’s API is the most widely accessed in the world. Here’s another example: if you've ever shopped online and seen the option to pay with PayPal, this is an indicator that the store is using PayPal’s API.

In short, mobile app development can take advantage of APIs by allowing users to interact with other programs, sharing information and data. This can create a seamless experience for users when it's necessary to have information from one site or service for use in another, separate mobile app.

When talking about mobile application APIs, it's important to mention REST APIs. REST is a development concept that is defined as an API that uses HTTP requests when utilizing data. It's an extremely popular methodology due to how it's developed using systems that are already well-established.

REST methodologies are the gold standard when it comes to building an API that allows your users to connect to all the various services they'll want to use. Google, Facebook, Twitter, and many other huge players in the tech space utilize REST APIs.

The reason these kinds of API methodologies exist is because making network requests on mobile apps can be cumbersome and lead to problems. There are a lot of different things developers need to be mindful of.

For one, developers need to have a thorough knowledge of the functionality of web services. There are a huge number of APIs that can be connected to, and many of these services are based on REST methodologies and architecture. It means that developers will be working with a lot of JSOT as this is the format of REST.

Also, developers need to possess a solid understanding of the HTTP protocol, which is what REST APIs are built for passing data back and forth. Moreover, devs need to be familiar with how HTTP uses URLs and how it moves data.

A lot of this API work with REST architecture will require URL mapping for requests. And depending on the API, every URL mapping is going to be different.

Finally, mobile developers need to be extremely knowledgeable of the networking APIs for the platform they’re working on, whether iOS or Android. Both platforms have extensive networking APIs and knowing them in and out is necessary when building networking mobile applications.

Now that we know a bit more about mobile application APIs, let’s take a look at some of the more popular APIs out there.


Facebook’s API is one of the most popular APIs. It’s extensively used in app development. This API allows apps and services to access and use profile information and friend lists to develop apps that are more social and better connected. Apps can be developed to update a user’s profile page, news feed, or other activities on Facebook. Also, users can add profile information to other applications by accessing their profile, friends list, subscribed pages, groups, photos, and event information. Facebook has four total APIs:

  • Facebook Marketing
  • Facebook Ad
  • Facebook Atlas
  • Facebook Graph

And, of course, Facebook’s API uses the REST architecture and returns all data in JSON format.


Twitter is another popular social API that’s utilized by mobile developers. Many developers use Twitter’s authentication system. Also, they allow users to post content or tweets from within their applications. Keep in mind, when allowing users to post from within your apps, your API keys can be revoked if a user violates the company’s policies.

Google Maps

The Google Maps API is immensely popular for custom mobile app development, giving developers access to an insane amount of mapping and traffic data, not to mention location tracking abilities. The difference with the Google Maps API, when compared to social media APIs, is that Google charges for the use of the API. You’ll have to pay fees for your mobile app to have access to Google Maps data. However, depending on the usage requirements of your application, you can opt to subscribe to only the services you need to save costs. Google has separated the mapping APIs into several sub-categories, including Static Maps API, Directions API, Street View Image API, and others.


Utilizing Google’s Gmail API, you can use a single sign-on for your application, making it easier for new users to run your app. A lot of users avoid creating new accounts when trying out a new app, so this can be a way to circumvent that avoidance and get users to utilize your service.


The popular video site has a robust API that gives users access to a plethora of video content. You can embed videos, video players, and even include YouTube search functionality in your app, bringing the experience of YouTube directly into your app and giving it a layer of interaction you might not otherwise have.


Facebook’s massively popular photo-sharing service has an API that can access Instagram’s user login service, friends, photos, and updates to a user’s timeline. It’s another great social media API that can add to your application.

The long and short of it is that APIs form a connection between your application and the massive amount of data that’s out there on other services. By utilizing these data and services, you’ll give your users a more robust experience in your application, making your app more valuable to them.

About the Author:
Joe Tuan is the founder and CEO of Topflight Apps, one of Southern California's best app design and development companies.