What is an API (Application Programming Interface)?

API, which stands for Application Programming Interface, is a list of operations that developers to use, along with the description of what they do for building and integrating application software.

To understand API better, let’s take a look at a popular example.

Imagine that you are sitting in a restaurant. You choose your choice items from the menu. Now, you have to convey your selections to the kitchen or ‘system.’ But how will you communicate your order to the kitchen? This is where the waiter or ‘API’ comes to play. The waiter (API) is your messenger who conveys your choice to the kitchen (system) and tells them what to do. Then, the waiter (API) delivers the results back to you which in this case is your selected food items.

API allows for your product/service communicate or interact with other products/services without having to understand how they are implemented. This can simplify app development, saving time and money. When you’re designing new tools and products or managing existing ones, APIs give you flexibility, simplify design, administration, and use; and provide opportunities for innovation.

Types of API

Let’s take a look at the different types of API.


REST, which stands for Representational State Transfer, is a web service API. It is a commonly used API category that is not dependent on a specific protocol. REST APIs are a key part of modern web applications, including Netflix, Uber, Amazon, and many others. For an API to be RESTful, it must adhere to the following rules:

A) Stateless: A REST API is stateless in nature, Client-Server Architecture

B) Uniform Interface: A client and server should communicate with one another via HTTP (Hyper Text Transfer Protocol) using URIs (Unique Resource Identifiers), CRUD (Create, Read, Update, Delete) and JSON (JavaScript Object Notation) conventions.

C) Client-Server: The client and server should be independent of each other. The changes you make on the server shouldn’t affect the client and vice versa.

D) Cache: The client should have the ability to cache the responses as this improves the user experience by making them faster and more efficient.

E) Layered: The API should support a layered architecture, with each layer contributing to a clear hierarchy. Each layer should be loosely coupled and allow for encapsulation.


SOAP, which stands for Simple Object Access Protocol, is an API that connects different platforms together through HTTP and XML. The structure and requirements for SOAP are more rigid than REST, and it’s defined by a specific protocol.

SOAP is an official protocol defined by the World Wide Web Consortium (W3C) and it comes with strict rules, especially in terms of security. However, those added security requirements make SOAP complex and, in some situations, very resource intensive. With the exception of niche use-cases, most developers prefer developing in REST.

3) RPC

RPC, which stands for Remote Procedure Calls, are the simplest and oldest types of APIs. The objective of an RPC is for the client to execute code on a server. XML-RPC uses XML to encode its calls, while JSON-RPC uses JSON for the encoding. Both are simple protocols. RPC is quite similar to REST, although there are a few key differences. RPC APIs are very tightly coupled, so this makes it difficult to maintain or update them.

To make any changes, a new developer would have to go through various RPCs documentation to understand how one change could affect the other.

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