What is an API — All the things you need to know-Part 1

Kushan Madhusanka
6 min readAug 23, 2022

I am gonna talk about API which is an essential part when it comes to application development. If you are becoming a programmer, I don’t think that you will be survived without knowledge of APIs. So, here is a good chance to learn all the things about API in the same place. From this article you will learn about :

what is an API ?

The way API works

Types of APIs

API specifications

Why do we need API

API testing tools

Features of API

What is an API ?

Technically, API stands for Application Programming Interface. But it doesn’t make any sense for a beginner. We need a simple idea. We can say API makes the connection between the user and the system. That means API is the messenger. It takes requests from the user and brings them to the system for some kind of action to be performed. Otherwise, we can say, API specifies how should interact software components with each other. As well as it is a set of protocols, routines, and tools to build applications.

The way API works

To understand how API works, let’s take a small scenario as an example. Imagine you are in a restaurant. You are hungry and you want some food. But you can’t go to the kitchen and eat whatever you want. You are an external person. So, you need someone who is able to do it for you. In restaurants, we have waiters to do that. You can say to the waiter what you want and the waiter will go to the kitchen and bring the food that you ordered. Here, the waiter is considered an API. Food is the data you want and the kitchen is the database. So, you have the connection to the kitchen through the waiter(API).

API types

There are mainly four different types of APIs commonly used. The “type” of the API, in this case, denotes the intended scope of use.

  • Private

Private APIs (or internal APIs) build to use only within an organization to make the connection between the system and data. For example, an internal API may link the payroll and HR systems of an organization.

  • Partner

Partner APIs are available for specific outside organizations or developers who are selected and authorized to use them. This type of API allows business-to-business activities.

  • Public

Public APIs are available to any outside developer or organization. So, there are no restrictions to use them.

  • Composite

These APIs are generated by using two or more APIs to execute a sequence of independent orations. Sometimes composite APIs can improve speed and performance over individual APIs.

Specifications of APIs

When API exchanges data, it requires some protocols and structures to govern these operations. Here I am gonna discuss a few different types.

  • Representational state transfer (REST)

This may be the most popular approach to building APIs and offers web-wide standards amongst computer systems which make communication flow easier. REST is stateless which means it doesn’t store any data or status between requests.

  • Service object access protocol (SOAP)

A lightweight protocol for transmitting structured information in a decentralized, distributed environment is what Microsoft defines as SOAP. SOAP APIs are usually used to create web APIs with XML. This supports a wide range of communication protocols such as HTTP, SMTP, and TCP. Developers are able to add features and functionalities easily because SOAP is extensible and style-independent.

  • GraphQL

This is a query language for APIs. You have the power to get the exact data because it offers an absolute and simplified description of the data. As a result, it is simpler to evolve APIs over time and sophisticated developer tools are made possible.

  • Remote procedural call (RPC)

This protocol is used to send multiple parameters and receive results. It invokes executable actions or processes. JSON and XML are two programming languages that RPC can use; these APIs are referred to as JSON-RPC and XML-RPC, respectively.

Why do we need APIs

When we access some resources APIs make it easier for us. As well as it allows us cross-platform communication.

  • APIs are efficient

API can reduce the time and workload of your organization since APIs can be hosted and created by a third party. This will speed up your development process. It makes it easier for you to efficiently incorporate content from any website or application.

  • APIs make things simpler

Through the APIs, you can get the data you need without conducting extra research. APIs reduce complexity by breaking down various business logic into manageable pieces. Additionally, they offer user-friendly endpoints specific to particular use cases. It enables the customer or business to personalize the services and content that they use most frequently.

API testing tools

APIs testing tools make developer's life easier. They don't have to wait for the whole software to be completely built. They can experience faster test maintenance and refactoring. As well as they can address more bugs and issues in less time compared to the UI test. There are a bunch of API testing tools in the market for your team to use. You can select one of them by considering some key factors.

  • Postwomen/hoppscotch

This is a free and fast API request generator. You can save time because it allows you to send requests and get/copy responses in real-time. Go to Hoppscotch from here.

Pricing- Free

  • Postman

Postman is a collaborative platform for API developments. Postman began as a Chrome plugin and then evolved into an on-premise solution for both Mac and Windows. Go to Postman from here or you can download the desktop application.

Pricing- Free-$12/user/month

  • SoapUI

SoapUI is a headless functional testing tool and allows users to test REST and SOAP APIs and web services with no hassles. There is a free package and a Pro package available for users. The free package has some restrictions. Go to SoapUI from here or download it.

Pricing-Free — $749/year

  • Karate

Karate is an open-source solution for tasks including UI automation, performance testing, and API test automation. Go to Karate from here

  • REST-assured

REST services can be tested more easily thanks to this open-source Java domain-specific language. Supports POST, GET, PUT, DELETE, OPTIONS, PATCH, and HEAD requests and users do not need to be an HTTP expert to utilize this tool. Go to REST-assured from here.


We have more tools like these :

Features of APIs

Here are a few key API features:

  • It aids in business model planning.
  • It provides a useful service (data, function, audience,.).
  • measured and managed.
  • Simple, flexible, and immediately adopted.
  • provides excellent developer assistance.

Now, we have come to the end of the article. So far we have discussed the definition of an API and how it works. APIs types also have been mentioned. And we discussed API specifications, API testing tools, features of APIs, and why we need APIs.

See you in the next blog post. Bye Bye🍻🍸❤️❤️



Kushan Madhusanka

Undergraduate of University of Moratuwa | Faculty of Information Technology