Aditi Dosi
4 min readSep 10, 2022


Application Programming Interface

An application programming interface is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build or use such a connection or interface is called an API specification.

APIs are needed to bring applications together in order to perform a designed function built around sharing data and executing pre-defined processes. They work as the middle man, allowing developers to build new programmatic interactions between the various applications people and businesses use on a daily basis.

The Google Maps API and Twitter API may be among the most widely used API examples, but most software-as-a-service (SaaS) providers offer APIs that let developers write code that posts data to and retrieves data from the provider’s site as well.

Four types of web APIs

APIs are broadly accepted and used in web applications. There are four principal types of API commonly used in web-based applications: public, partner, private and composite. In this context, the API “type” indicates the intended scope of use.

Public APIs. A public API is open and available for use by any outside developer or business. An enterprise that cultivates a business strategy that involves sharing its applications and data with other businesses will develop and offer a public API.

Partner APIs. A partner API, only available to specifically selected and authorized outside developers or API consumers, is a means to facilitate business-to-business activities. For example, if a business wants to selectively share its customer data with outside CRM firms, a partner API can connect the internal customer data system with those external parties — no other API use is permitted.

Internal APIs. An internal (or private) API is intended only for use within the enterprise to connect systems and data within the business. For example, an internal API may connect an organization’s payroll and HR systems.

Composite APIs. Composite APIs generally combine two or more APIs to craft a sequence of related or interdependent operations. Composite APIs can be beneficial to address complex or tightly-related API behaviors, and can sometimes improve speed and performance over individual APIs.

API protocols and architectures

APIs exchange commands and data, and this requires clear protocols and architectures — the rules, structures and constraints that govern an API’s operation. Today, there are three categories of API protocols or architectures: REST, RPC and SOAP.


SOAP stands for Simple Object Access Protocol. With this architectural style, the client and the server communicate with each other using XML. This type of API is popular due to its rigid structure and independence from any specific programming language. While less common than they once were, many organizations still use SOAP APIs.

Examples of SOAP APIs include…

  • Salesforce SOAP API
  • Workday SOAP API
  • Sabre SOAP API


The acronym REST stands for Representational State Transfer. With a REST API, the client and server may communicate with one another using XML, but they aren’t limited to that specific language. This type of API is also more flexible. Think of it as a style guide rather than a strict standard.

What is a REST API example?

For example, a REST API would use a GET request to retrieve a record, a POST request to create one, a PUT request to update a record, and a DELETE request to delete one. All HTTP methods can be used in API calls. A well-designed REST API is similar to a website running in a web browser with built-in HTTP functionality.

What is Postman API?

The Postman API endpoints enable you to integrate Postman within your development toolchain. You can add new collections, update existing collections, update environments, and add and run monitors directly through the API. This enables you to programmatically access data stored in your Postman account.

Why Should You Use an API?

Computers make many things easier, especially tasks that involve collecting and sorting through vast quantities of data. Gone are the days of searching locally hosted spreadsheets or even digging through filing cabinets in search of the information you want to access. Now, there are databases. If computers are making everything simpler, a quick query should result in everything you need, right?

If your company uses a customer relationship management (CRM) system like Salesforce, the data you are looking for is probably somewhere in their cloud storage. To access it, you will likely need to use an API.

Think about the Google Maps API. Rather than building a web mapping platform, companies like Uber can use the API to incorporate Google’s.

While using an API may seem like unnecessary added work, they are meant to improve information security and the ease with which you can access the data you need to make well-informed business decisions. Unfortunately, ease of use is relative. If you aren’t an IT professional, the prospect of learning how to use an API can seem daunting at first.