SDK vs. API: What's the Difference?

By Indeed Editorial Team

Published July 27, 2021

Web developers use a variety of tools to help them build applications and websites. Both SDKs and APIs allow programmers to use third-party data in their designs. Understanding how both of these tools work allows you to determine which one to use in your project. In this article, we discuss what SDKs and APIs are, explain the differences between the two and provide some examples of both.

What are SDKs?

Software development kits (SDKs) are a set of tools, programs and guidelines for developing applications to a specific platform, such as an app. Companies often make their SDKs available to help computer developers integrate their services easily. For instance, a video conferencing company may share their SDK with programmers so that they can integrate it on their website. Common utilities SDKs may include are:

  • APIs

  • Integrated Drive Electronics (IDE)

  • Code samples

  • Libraries

  • Relevant documentation and instructions

  • Network protocols

  • Examples and test products

Related: What Is an App? Types of Apps and Examples

Why are SDKs important?

SDKs use pre-written code to reduce the complexity of developing applications or software. This allows programmers to use pre-built functionality, rather than building it from scratch. Another benefit of SDKs is that it improves the process for integrating new tools. It helps them avoid work duplication and helps them save time in their development. SDKs also help enhance the overall experience for app users. Other benefits of using SDKs include:

  • Saving money through the reduction of time spent on the project

  • Ensuring secure features

  • Releasing products before competitors

Related: How To Become a Computer Engineer

What are APIs?

Application programming interfaces (APIs) are sets of tools and protocols to build software. This allows an application to interact with an external service using a set of commands. For instance, a shop website may use an API to allow users the option to pay through a different platform. Any time someone uses an application, the application connects to the internet, sending data to a server. Once the server retrieves the data, it interprets it and performs necessary actions before sending users the information they requested. APIs are the foundational blocks that allow programmers to create a project.

Related: What Are Applications?

Why are APIs important?

An API allows an application to use capabilities from another application. Using APIs helps computer programmers to speed up their development process and allows for consistency. Some benefits of using APIs include:

  • Allowing programmers to add features to their apps quickly and easily

  • Helping users perform tasks, such as sharing an article

  • Improving navigation through interconnected sources

  • Creating time to focus on building innovative apps

SDK vs. API

While computer programmers use both APIs and SDKs to help them create websites and applications, each tool has its own advantages and functions. Here are the primary differences between APIs and SDKs:

Purpose

An API serves the specific function of allowing communication between applications. These work well if a programmer is looking to facilitate interactions between applications. Programmers can use APIs to add specific functions to an application. However, if they are looking to build a brand-new app or website, SDKs provide them with the tools needed since they allow programmers to add many functions. SDKs often contain APIs since their new applications need to be able to communicate with other applications.

Usage

One of the main differences between an API and SDK is how a programmer uses them. For an SDK, the programmer downloads the package onto their computer and incorporates it within their project. The download includes utilities, such as APIs and libraries, to help programmers use it. When using an API, a programmer submits a request to the server following the API's guidelines. Once the server receives the request, programmers get a response containing the desired data.

Characteristics

An API tends to be lightweight and fast. It's also specialized to serve one particular function, with only the function descriptions and functionalities included. APIs represent the plumbing system that provides water throughout the house, whereas SDKs represent the entire house. SDKs are more robust and contain many utilities. They often include sample codes, technical documents and debugging tools.

Related: Web Developer Skills: Definitions and Examples

Examples of SDKs and APIs

Here are some examples of companies using SDKs and APIs:

SDK example

A movie streaming website offers two options for users to log in to their website. Visitors can either create a new account with their website or log in using their social media credentials. Having the latter option helps makes the process easier for users. To implement this option, the movie streaming website uses an SDK package. The SDK gives them a pre-written code to use, with instructions on how to implement the login option on their website. This saves the movie streaming company time and energy since they can use the pre-written code, rather than building their own.

API example

The Moodzic app creates a playlist for listeners based on the weather in their area and the designated mood for the weather, such as happy tunes for sunny weather. Listeners enter their zip code, and the company generates a playlist based on the current condition of their location's weather. This allows users to access a playlist based on their area's weather without leaving Moodzic's website.

To accomplish this, Moodzic uses APIs for the weather and music streaming. After entering your zip code, Moodzic sends a request to a weather API to receive the weather conditions in your area. Moodzic then uses that data to send a request to a music streaming service that builds a playlist based on the mood related to the weather.

Related: How To Become an App Developer

How can I choose between using an SDK and an API?

When determining whether to use an SDK or API, consider what function you want it to serve. Choosing between using an API or SDK depends on whether you want to add a few features to your project or start from the beginning.

If you need a tool to help you build an app, an SDK is a great option since it gives you a starting point. However, if you're looking for something to help your app communicate with a third-party service provider, select an API since its main purpose is to allow communication between two platforms. There are some instances where you may use both an SDK and an API since APIs help your newly created app communicate with other platforms.

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