SDK & API – why those 2 tools usually go hand in hand

December 13, 2021

When developing software, you’ll frequently encounter the terms API (Application Programming Interface) and SDK (Software Development Kit). Both are crucial tools and have a lot in common. At their core, both APIs and SDKs are used to add functionality to a mobile application or website. For non-developers, the terms often seem interchangeable, which causes incorrect use and confusion. To deliver a flawless experience both in-house and for end-users, it’s necessary to understand their differences, how they work, and what role they play in the development process. Dive into the subject with us and get full insight into the topic in the following blog post. 

First step – defining SDK and API

As stated above, SDK is short for “software development kit,” while API stands for “application programming interface.” 

An SDK is a sophisticated collection of software development tools created for a specific purpose. It facilitates the development of applications for a particular software package, framework, hardware platform, or operating system by providing fully-developed functions that can be integrated directly. They usually include APIs that enable different functionalities within the Software Development Kit to interact. 

As the name already suggests, an API is the interface required to connect different software components or web services. It consists of a set of protocols and rules. This lets developers build application software with clearly defined methods of communication between the various components. APIs also allow third-party developers to leverage proprietary software. In this way, APIs enable app users to access services that don’t belong to the actual provider of the application. 

Simply put, APIs are interfaces for services. However, they never provide functionality in themselves the way SDKs do.  

All in one – which tools are included in a standard SDK? 

A software development kit consists of several components needed to create software for a specific platform. 

Usually, an SDK includes some or all of the following resources: 

Generally, SDKs include one or more APIs, because apps can’t transfer information and interact without a suitable interface.

Let’s get practical – how does an SDK work?

Now that we’ve discussed the tools included in an SDK, let's take a look at the process of creating a mobile app with a standard Software Development Kit:

  1. The SDK must be downloaded and installed on the chosen development platform.  
  2. You can now access its assets – for instance, APIs or compilers – in an integrated development environment (IDE). This is where developers do the actual coding. 
  3. The included instructions, code samples, documentation, and testing tools provide all necessary assistance and resources for a good start to a new project.

Application Programming Interfaces – Major impact with 2 key components

No matter whether used by an application internally or as a standalone solution, an API always enables communication between two or more components or programs. To be usable, it needs to provide two core components: 

Common types of APIs include Web APIs, SOAP APIs, open and custom APIs, and REST APIs. 

Technically, a call to a Web API includes the following steps: 

  1. An app user initiates a task. We’ll take adding a meeting to an external calendar as an example. 
  2. The API embedded in the app now sends this request to the API endpoint. In our example, that’s the calendar service’s web server.
  3. Now, the task requested is executed by the third-party application or database service provider. Here, the new meeting is added to the calendar provider’s database.

Mobile applications usually include offline APIs as well. These do connect to an external provider, but work exclusively inside the device. The workflow here looks like the following:

  1. An app user initiates a task, for example, taking a new profile picture. 
  2. Now, the API connects the application to the external service. In our case, that’s the smartphone’s camera app. 
  3. The task is now executed by that service. Here, the phone’s camera app takes a picture to send back to the initial app. 

SDK or API – do you have to choose between these tools? 

No. As mentioned before, SDKs usually include at least one API. Both tools support software development, and though they do so in different ways, they work together in countless cases.

As described above, APIs determine how different platforms work together. However, they are interfaces – they don’t provide any functionality in themselves. Thus, they are just one part of the entire toolkit required to create an application. 

In contrast, SDKs provide the complete kit, including APIs. Unlike APIs, they don’t just facilitate specific tasks. Rather, they offer bundles of assets that simplify building entire apps, often across several platforms and programming languages. 

To ensure the highest data privacy, offline-based solutions are crucial. Especially since SDKs usually contain sets of different APIs, businesses need to ensure that those interfaces are offline APIs that do not connect to any external servers but work solely on the end user's deviceSDK & API – why those 2 tools usually go hand in hand 

When developing software, you’ll frequently encounter the terms API (Application Programming Interface) and SDK (Software Development Kit). Both are crucial tools and have a lot in common. At their core, both APIs and SDKs are used to add functionality to a mobile application or website. For non-developers, the terms often seem interchangeable, which causes incorrect use and confusion. To deliver a flawless experience both in-house and for end-users, it’s necessary to understand their differences, how they work, and what role they play in the development process. Dive into the subject with us and get full insight into the topic in the following blog post. 

First step – defining SDK and API

As stated above, SDK is short for “software development kit,” while API stands for “application programming interface.” 

An SDK is a sophisticated collection of software development tools created for a specific purpose. It facilitates the development of applications for a particular software package, framework, hardware platform, or operating system by providing fully-developed functions that can be integrated directly. They usually include APIs that enable different functionalities within the Software Development Kit to interact. 

As the name already suggests, an API is the interface required to connect different software components or web services. It consists of a set of protocols and rules. This lets developers build application software with clearly defined methods of communication between the various components. APIs also allow third-party developers to leverage proprietary software. In this way, APIs enable app users to access services that don’t belong to the actual provider of the application. 

Simply put, APIs are interfaces for services. However, they never provide functionality in themselves the way SDKs do.  

All in one – which tools are included in a standard SDK? 

A software development kit consists of several components needed to create software for a specific platform. 

Usually, an SDK includes some or all of the following resources: 

Generally, SDKs include one or more APIs, because apps can’t transfer information and interact without a suitable interface.

Let’s get practical – how does an SDK work?

Now that we’ve discussed the tools included in an SDK, let's take a look at the process of creating a mobile app with a standard Software Development Kit:

  1. The SDK must be downloaded and installed on the chosen development platform.  
  2. You can now access its assets – for instance, APIs or compilers – in an integrated development environment (IDE). This is where developers do the actual coding. 
  3. The included instructions, code samples, documentation, and testing tools provide all necessary assistance and resources for a good start to a new project.

Application Programming Interfaces – Major impact with 2 key components

No matter whether used by an application internally or as a standalone solution, an API always enables communication between two or more components or programs. To be usable, it needs to provide two core components: 

Common types of APIs include Web APIs, SOAP APIs, open and custom APIs, and REST APIs. 

Technically, a call to a Web API includes the following steps: 

  1. An app user initiates a task. We’ll take adding a meeting to an external calendar as an example. 
  2. The API embedded in the app now sends this request to the API endpoint. In our example, that’s the calendar service’s web server.
  3. Now, the task requested is executed by the third-party application or database service provider. Here, the new meeting is added to the calendar provider’s database.

Mobile applications usually include offline APIs as well. These do connect to an external provider, but work exclusively inside the device. The workflow here looks like the following:

  1. An app user initiates a task, for example, taking a new profile picture. 
  2. Now, the API connects the application to the external service. In our case, that’s the smartphone’s camera app. 
  3. The task is now executed by that service. Here, the phone’s camera app takes a picture to send back to the initial app. 

SDK or API – do you have to choose between these tools? 

No. As mentioned before, SDKs usually include at least one API. Both tools support software development, and though they do so in different ways, they work together in countless cases.

As described above, APIs determine how different platforms work together. However, they are interfaces – they don’t provide any functionality in themselves. Thus, they are just one part of the entire toolkit required to create an application. 

In contrast, SDKs provide the complete kit, including APIs. Unlike APIs, they don’t just facilitate specific tasks. Rather, they offer bundles of assets that simplify building entire apps, often across several platforms and programming languages. 

To ensure the highest data privacy, offline-based solutions are crucial. Especially since SDKs usually contain sets of different APIs, businesses need to ensure that those interfaces are offline APIs that do not connect to any external servers but work solely on the end user's device. 



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