What is an API (Application Programming Interface)?

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Everyone is successful hunt of nan highest-paying occupation truthful arsenic to get into it. And, successful nan list, nan web developer is connected nan apical for years and will stay successful nan aforesaid spot owed to its demand. If you’re nan 1 who’s looking for getting into it. you must beryllium alert of nan astir important position utilized successful it. Out of each nan terms, API is yet different word that plays a very important domiciled while building a website. Now, what is an API – (Application Programming Interface)?

API (Application Programming Interface)

To make you clear pinch nan dia of what is an API, let’s return a real-life illustration of an API, you tin deliberation of an API for illustration a waiter successful a edifice who listens to your bid request, goes to nan chef, takes nan nutrient items ordered and gets backmost to you pinch nan order. Also, if you want to look for nan moving of an API pinch nan example, here’s one. You’re searching for a course(let’s opportunity DSA-Self Paced) on nan XYZ website, you nonstop a request(product hunt requested) done an API, and nan database searches for nan people and checks if it’s available, nan API is responsible present to nonstop your petition to nan database (in hunt of nan course) and responds pinch nan output(best DSA courses).

What is an API?

API is an abbreviation for Application Programming Interface which is simply a postulation of connection protocols and subroutines utilized by various programs to pass betwixt them. A programmer tin make usage of various API devices to make their programme easier and simpler. Also, an API facilitates programmers pinch an businesslike measurement to create their package programs. Thus successful simpler terms, an API helps 2 programs aliases applications to pass pinch each different by providing them pinch nan basal devices and functions. It takes nan petition from nan personification and sends it to nan work supplier and past again sends nan consequence generated from nan work supplier to nan desired user. 

A developer extensively uses APIs successful his package to instrumentality various features by utilizing an API telephone without penning analyzable codes for nan same. We tin create an API for an operating system, database system, hardware system, JavaScript file, aliases akin object-oriented files. Also, an API is akin to a GUI(Graphical User Interface) pinch 1 awesome difference. Unlike GUIs, an API helps package developers to entree web devices while a GUI helps to make a programme easier to understand by users. 

How do APIs Work?

The moving of an API tin beryllium intelligibly explained pinch a fewer elemental steps. Think of a client-server architecture wherever nan customer sends nan petition via a mean to nan server and receives nan consequence done nan aforesaid medium. An API acts arsenic a connection mean betwixt 2 programs aliases systems for functioning. The customer is nan user/customer (who sends nan request), nan mean is nan API, and nan server is nan backend (where nan petition is accepted and a consequence is provided). Steps followed successful nan moving of APIs –

  • The customer initiates nan requests via nan APIs URI (Uniform Resource Identifier)
  • The API makes a telephone to nan server aft receiving nan request
  • Then nan server sends nan consequence backmost to nan API pinch nan information
  • Finally, nan API transfers nan information to nan client

APIs are considered safe successful position of attacks arsenic it includes authorization credentials and an API gateway to limit entree truthful arsenic to minimize information threats. To supply further information layers to nan data, HTTP headers, query drawstring parameters, aliases cookies are used.

If we talk astir nan architectures, API’s architectures are:

  • REST (Representational State Transfer) 
  • SOAP (Simple Object Access Protocol) 

Both specify a modular connection protocol for nan speech of messages successful XML (Extensible Markup Language). 

How is an API Different From a Web Application?

An API acts arsenic an interface that allows due connection betwixt 2 programs whereas a web exertion is simply a network-based assets responsible for completing a azygous task. Also, it’s important to cognize that “All web services are APIs, but not each APIs are web”.

The quality betwixt an API and a web exertion is that API allows two-way connection and web applications are conscionable a measurement for users to interact done a web browser. A web exertion whitethorn person an API to complete nan requests. 

Types of APIs

There are 3 basal forms of API – 


A Web API besides called Web Services is an extensively utilized API complete nan web and tin beryllium easy accessed utilizing nan HTTP protocols. A Web API is an open-source interface and tin beryllium utilized by a ample number of clients done their phones, tablets, aliases PCs. 


In this type of API, nan programmers get nan section middleware services. TAPI (Telephony Application Programming Interface), and .NET are communal examples of Local APIs.


It makes a distant programme look to beryllium section by making usage of RPCs (Remote Procedural Calls). SOAP is simply a well-known illustration of this type of API.

Few different types of APIs:

  • SOAP (SIMPLE OBJECT ACCESS PROTOCOL): It defines messages successful XML format utilized by web applications to pass pinch each other.
  • REST (Representational State Transfer): It makes usage of HTTP to GET, POST, PUT, aliases DELETE data. It is fundamentally utilized to return advantage of nan existing data.
  • JSON-RPC: It uses JSON for information transportation and is simply a lightweight distant procedural telephone defining a fewer information building types.
  • XML-RPC: It is based connected XML and uses HTTP for information transfer. This API is wide utilized to speech accusation betwixt 2 aliases much networks.

What are REST APIs?

REST stands for Representational State Transfer, and follows nan constraints of REST architecture allowing relationship pinch RESTful web services. It defines a group of functions (GET, PUT, POST, DELETE) that clients usage to entree server data. The functions utilized are:

  • GET (retrieve a record)
  • PUT (update a record)
  • POST (create a record)
  • DELETE (delete nan record)

Its main characteristic is that REST API is statelessness, i.e., nan servers do not prevention clients’ information betwixt requests. 

What is simply a Web API?

Web API Is simply an API for nan web. It is an API that tin beryllium accessed utilizing nan HTTP protocol. It tin beryllium built utilizing Java, .nET, etc. It is implemented to widen nan functionality of a browser, simplify analyzable functions, and supply easy syntax to analyzable code. 

The 4 main types of web APIs are:

  • Open API
  • Partner API
  • Internal API
  • Composite API

To Know More: What is Web API and why we usage it?




SOAP (Simple Object Access Protocol) is simply a protocol pinch circumstantial requirements for illustration XML messagingREST (Representational State Transfer) is simply a group of guidelines (architectural style) offering elastic implementation
Heavier and needs much bandwidthLightweight and needs little bandwidth
It defines its ain securityIt inherits information from nan underlying transport
It permits XML-based information format onlyIt permits different information formats specified arsenic plain text, HTML, XML, JSON, etc.
SOAP calls cannot beryllium cachedREST calls tin beryllium cached

Also, nan awesome quality is that SOAP cannot make usage of REST whereas REST tin make usage of SOAP. You tin besides publication astir nan difference betwixt REST API and SOAP API 

What is API Integration?

API Integration is nan relationship betwixt 2 aliases much applications, via APIs, letting you speech data. It is simply a mean done which you tin stock information and pass pinch each different by involving APIs to let web devices to communicate. Due to nan emergence successful cloud-based products, API integration has go very important. 

What is API Testing?

API Testing is simply a benignant of package testing that analyzes an API successful position of its functionality, security, performance, and reliability. It is very important to trial an API truthful arsenic to cheque whether it’s moving arsenic expected aliases not. If not, again changes are made successful nan architecture and re-verified. 

APIs are nan halfway of package improvement to speech information crossed applications. The API testing includes sending requests to single/multiple API endpoints and validating nan response. It focuses majorly connected business logic, information responses and security, and capacity bottlenecks.

Types of Testing:

  • Unit Testing
  • Integration Testing
  • Security Testing
  • Performance Testing
  • Functional Testing

Must Read: API Testing successful Software Testing

API Testing Tools:

  • Postman
  • Apigee
  • JMeter
  • Ping API
  • Soap UI
  • vREST

How to Create APIs?

Creating an API is an easy task unless you are very good clear connected nan basal concepts. It’s an iterative process (based connected feedback) that conscionable includes a fewer easy steps:

  • Plan your extremity and nan intended users
  • Design nan API architecture 
  • Develop (Implement nan code) and Test API 
  • Monitor its moving and activity connected feedback

Must Read: Tips for Building an API

Restrictions of Using APIs

When an API is made it’s not really released arsenic package for download and it has immoderate policies governing its usage aliases restricting its usage to everyone, usually location are 3 main types of policies governing APIs, those are:

  • Private: These APIs are only made for a azygous personification aliases entity (like a institution that has spent nan resources to make it aliases bought it).
  • Partner: Just for illustration nan sanction it gives nan authority to usage APIs to immoderate partners of entities that ain APIs for their backstage use. 
  • Public: You should beryllium alert of them origin you tin only find these APIs successful nan marketplace for your ain usage if you don’t ain circumstantial API entree from immoderate entity that owns backstage these APIs for their backstage use. An illustration of a Public API is ‘Windows API’ by Microsoft for much nationalist APIs you tin sojourn this GitHub repository ->

Advantages of APIs 

  • Efficiency: API produces efficient, quicker, and much reliable results than nan outputs produced by quality beings successful an organization.
  • Flexible transportation of services: API provides accelerated and elastic transportation of services according to developers’ requirements.
  • Integration: The champion characteristic of API is that it allows nan activity of information betwixt various sites and frankincense enhances nan integrated personification experience.
  • Automation: As API makes usage of robotic computers alternatively than humans, it produces amended and much automated results.
  • New functionality: While utilizing API nan developers find caller devices and functionality for API exchanges.

Disadvantages of APIs 

  • Cost: Developing and implementing API is costly astatine times and requires precocious attraction and support from developers.
  • Security issues: Using API adds different furniture of aboveground which is past prone to attacks, and hence nan information consequence problem is communal successful APIs.


By now, you must person had a clear thought of What is API? it’s working, types, testing devices used, etc. After knowing these concepts, you tin effort moving connected them by implementing immoderate of nan concepts successful projects. Not conscionable theoretical knowledge, you must besides person a applicable thought of it by moving connected it. Developers must person a heavy knowing of APIs successful bid to instrumentality them.


1. What API means?

Ans. Application Programming Interface (API), often referred to arsenic web API, is an interface that allows 2 systems to pass pinch each different (share information and entree resources). One of its purposes includes making visible nan soul specifications of really a strategy useful to only those that a programmer finds required. 

2. What are nan 4 types of API?

Ans. The 4 awesome APIs commonly utilized successful web-based applications are:

  • Public
  • Partner
  • Private
  • Composite

Also, immoderate of nan different APIs based connected its services include:

  • Web
  • Local
  • Program

3. What is an illustration of an API?

Ans. We tin return Zomato arsenic an illustration to explicate nan conception of an API. Zomato receives a petition for an order, nan customer tin way nan driver’s location. Here, nan API functions successful this way- nan Zomato app integrates pinch Google Map wherever aft integration, google maps thief you to way nan location. 

4. Which API is astir used?

Ans. The astir utilized APIs are nan societal media APIs wherever developers tin entree information from societal media platforms for illustration Facebook, Instagram, etc. Each societal media has its ain API that tin beryllium utilized by developers to interact pinch nan platform’s data. 

Editor: Naga

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