Do You Know Your API From An SDK?

In the mobile app development world, it has become increasingly important to understand the difference between an API (Application Programming Interface) and an SDK (Software Development Kit) and to recognize when you need to use each to most effectively develop your mobile apps. In today’s app development landscape, the synchronicity between APIs and SDKs have emerged as the driving force behind web communication and the implementation of third party APIs.

If you work at developing mobile apps every day, the difference and proper use might be second nature to you.  Our experience suggests that is not true, but let us proceed with that assumption. The larger issue is that business function management leaders almost certainly do not understand the first thing about the two concepts and how their organization can use them in the proper manner to most effectively and efficiently improve mobile enterprise app development and performance.  This is important as more and more app development investment is being done at the business function level.

Sooooooo, to help move things along, we wanted to share what is meant when we talk about APIs and SDKs including how they interact with each other, how to effectively use them and how widespread SDKs have become.

API (Application Programming Interface)

True to its name, an API is an “interface” that allows software to interact with other software. It is comprised of a set of subroutine definitions, protocols, and tools for building application software. In general terms, it's a set of clearly defined methods of communication between various software components. A good API makes it easier to develop a computer program by providing all the key building blocks.

Pretty much any app you use on a daily basis, whether for personal or business use, includes numerous APIs that provide much of the functionality of the app.  This is true even for computer-based applications, like copying and pasting within word processing or presentation software.  Web and mobile app APIs are critical to realizing the functionality of the apps in which they are used.  Hungry while visiting a town for business or pleasure?  When you open Yelp and search for your desired cuisine, the app uses an API to send the request to a back-end database.  Web APIs allow for interaction between disparate systems, often for specific use cases. For instance, when a user interacts on Twitter, they’re utilizing an API to comment, to store their data, to follow a user, to delete tweets, and so forth.   Perhaps most important is the fact that APIs deliver consistent coding in stable environments.

SDK (Software Development Kit)

A software development kit (SDK or "devkit") is typically a set of software development tools that allows the creation of applications for a certain software package, software framework, hardware platform, computer system, video game console, operating system, or similar development platform. To enrich applications with advanced functionalities, advertisements, push notifications and more, most app developers implement specific software development kits. Some SDKs are critical if you wish to develop an iOS/ Android app.

An SDK provides a set of tools, libraries, relevant documentation, code samples, processes, and or guides that allow developers to create software applications on a specific platform. Their more expansive and sophisticated code facilitates the creation of functionality that far exceeds what an API would deliver.

SDKs are the origination sources for almost every program a modern user would interact with. From the web browser you work on all the way to the video games you play at the end of the day, many were first built with an SDK, even before an API was used to communicate with other applications 

Which to Choose/Use

The fact is that, more often than not, an SDK contains an API.  By definition, an SDK is a kit that includes instructions that allows developers to create systems and develop applications. APIs, on the other hand, are purpose built for an express use — to allow communication between applications.

When you use an SDK to create an application that is required to communicate with other applications, you need an API to provide that functionality. But, the inverse is not true as an API can be used for communication within the app but is not broad and deep enough functionally to support the creation of a new app itself.