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apis and their architecture types

Why Should You Care About APIs and Their Types? Detailed Explanation

Mihir Mistry,

Do you ever ponder what spells your food delivery or online shopping app casts when you sign up with your social media account and automatically set up your profile? Actually, when you sign up with Facebook (or any social media account), the application establishes a relationship with your social media app. 

The app then converses with Facebook through an API and exchanges data with one another. That’s how the app gets your information and creates your basic profile on their app. And that’s the same reason when you search a term on a shopping app you signed up using Facebook; Facebook shows you the similar item’s ads the very next day.

In the software world, you hear the abbreviation API in every other sentence during developer conversations, and it can be intimidating if you don’t know what the term means. There’s a risk of missing the crux of the discussion as well. Yes, because API stands for Application Programming Interface, it is indispensable in app development

So why not understand what an API is and why it is so important in software development once and for all? Getting familiar with APIs can help you decide what will work for your application, avoiding potential pitfalls. For developers, the knowledge of API prevents them from doing redundant tasks. On that note, without further delay, let’s begin with the definition of API.

apis and their architecture types

What is an API?

An Application Programming Interface is a set of protocols under which a website or mobile application communicates with an external technology product using simple commands. Think of it as a language two technology products use to communicate. 

A user tries to get the weather forecast on the weather app, so the app sends a request to a server over a specific address. The request contains clear instructions, such as the weather in California today with an access key. Once the message is delivered, the weather API will respond over the same channel.

APIs contain two components:

  • Specification: The data exchange between technology products according to technical specifications to determine how to retrieve the data.
  • Interfaces: The interface is written to ensure communication between two applications.

An API is a kind of a contract, determining input and output data and how users connect and perform operations on the software. 

How do APIs Work?

So far, we understand, APIs enable communication between two software products. Now, let us comprehend how it does that after all.

Say you are at a restaurant and a waiter takes your order. Now, the waiter reports your order to their kitchen. The kitchen prepares your food, and the waiter serves it on your table.

Here, you are one program that orders food, and the kitchen is another program. The waiter who takes, reports, and serves the orders is the API that receives requests, processes, and returns the output. Unlike the waiter who returns your order, API presents the data or other functionality in return.

apis and their architecture types

Why do we use API in software development?

Major applications we use daily rely on various APIs to an extent. You can find APIs nearly for all categories from data, payment, weather, travel to map, and even sports. Using an API allows developers to add specific functionalities to their applications and speed up the development process. 

Say, for example, rather than creating an in-app message system from scratch, use Twilio SMS API instead. It will save a lot of time and resources. Therefore, we can say API are like building blocks for software development. APIs speed up development, preventing developers from reinventing the wheel by developing functionality that already exists.

Different Types Of APIs—Application Programming Interfaces

API design varies depending on request and response structure and format. Thus, developers have to pick APIs considering the development environment, programming language, available resources, etc. So, let’s comprehend the types of APIs to disguise which ones are right for your application.

Types of APIs by their availability

  • Open APIs: Also known as Public and external APIs. These APIs are publicly accessible for any third-party developers. Though available for all, you can find two types of external APIs: open (free of charge) and commercial ones. Developers can create and test applications with open API freely. In contrast, commercial APIs users pay subscription fees.

Such APIs are majorly used for increasing brand awareness and nurturing external innovations. Therefore, Public APIs can be an excellent way for startups to create useful applications. Google Places API, Google Analytics API, Upwork API, and YouTube API are some Open APIs.

  • Partner APIs: Unlike public APIs, not everyone can access Partner API. The publisher grants access to these APIs under specific terms & conditions. Commonly, Partner APIs are used to enable communication and integration of software between a company and its business partner. Developers have to purchase this type of APIs on a one-time payment or subscription basis. 
  • Internal APIs: AKA Private APIs are used for integration of the company’s internal systems and applications. Most in-house developers use these APIs to build enterprise-level solutions like CRM systems, ERP software, HRS solutions, etc. 
  • Composite APIs: These APIs are significantly complicated APIs that combine different data and service API. Composite APIs are designed to simplify integrating clients’ software by approaching batch API requests into a single API call. Thereby, it aims at boosting the execution process with improved performance. 

Take Composite API Salesforce as an example that executes a series of REST API requests in a single call. You can use the output of one request as the input to a subsequent request. The entire series of recommendations count as a single call toward your API limits.

apis and their architecture types

Types of APIs by their architecture and protocols

  • SOAP (Simple Object Access Protocol): 

It is a protocol used for exchanging structured information in a distributed environment. SOAP-based API create, recover, update and delete records, including accounts, leads, passwords, and custom objects. Large organizations use SOAP as it gives extensible flexibility and control over client/server interactions.


Remote Procedure Call is a protocol that specifies data transmission between client/server-based applications. XML-RPC APIs use XML, while JSON-RPC uses JSON format to execute several operations during a single call. 

  • REST (Representational State Transfer): 

REST, aka RESTful API, is not a protocol but a set of architectural principles for web development. It’s the best structure to meet the stateless architecture-based app’s requirements that depend on external storage. Because REST structure is designed to render high performance under heavy load. With load balancers, it allocates the workload accurately. Consequently, processing millions of requests every minute won’t halt the operation, reducing network latency. 

That’s all for what I could put APIs into the words. Hope this guide answers your questions about what an API is, how it works, and its types. If your curiosity to know API very well extends, feel free to raise your questions by connecting us. We can also estimate the cost of developing an API.

Mihir Mistry

Mihir Mistry is a highly experienced CTO at Kody Technolab, with over 16 years of expertise in software architecture and modern technologies such as Big Data, AI, and ML. He is passionate about sharing his knowledge with others to help them benefit.

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