10 Popular API Examples: A Full List

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Every time you use an app such as Facebook or Instagram, check the weather or send an instant message, you’re using an API. API examples are everywhere, in the applications you use on a daily basis. 

APIs are basically the middlemen of apps and web services, allowing different applications to communicate with each other. They are a key aspect of our digital world and in software development. With APIs, we are able to engage in digital experiences on our phones and computers every day. 

So what are APIs and some API examples? Here we will explain the concept of API in the most understandable way and provide you with 10 most popular examples of API. Understanding APIs is understanding how our fascinating digital world works. 

In this article, you will get to learn about:

  1. Twitter API
  2. ChatGPT API
  3. Google Map API
  4. Discord API
  5. Github API
  6. Paypal API
  7. eCommerce API
  8. YouTube API
  9. Instagram API
  10. Slack API

What is an API?

We’ll explain the concept of an API from both a technical and non-technical point of view.

From a technical perspective, APIs, or Application Programming Interfaces, are a set of protocols, routines, and tools for building applications. An API defines how different software components should interact with each other, allowing developers to create software applications that can interact with other applications, services, or platforms.

APIs allow developers to access functionality or data provided by a remote service or application through a standardized interface, without needing to understand the underlying code or infrastructure of the service. With an API, developers can build applications that integrate with other systems and services.

In other words, APIs allow application A to connect with application B.

API Examples

Let’s look at APIs from a more common and non-technical perspective.

Suppose that we have a weather app and a messaging app. Here's a simple explanation of an API using these two apps:

In this example, the weather app wants to provide weather updates to the messaging app. To perform this, the weather app developers create an API that exposes specific functions and data related to weather information. 

The messaging app developers can then integrate this weather API into their app. They use the API to send requests for weather updates, such as the current temperature or forecast, to the weather app's server.

In a way, an API is like a bridge or a middleman that connects two different apps. If application A wants to gain access to information/functionality from application B, it sends out an instruction (i.e. the API). Application B reads the instruction, and returns the requested information to application A.


Read More: What is API Testing? A Complete Guide

How To Use An API?

To use an API, you first need to find the API documentation, which will tell you how to make requests to the API and what responses to expect. APIs use specific URLs and protocols to receive and send data, and you'll need to use a programming language or tool that supports HTTP requests to interact with the API.

Once you know how to make requests, you'll need to create an API key or access token, which is a unique identifier that lets the API know who is making the request. You'll include this key or token in your requests to the API.

After you've made a request, the API will send back a response in a specific format, such as JSON or XML, which your program can parse and use to display data or perform other actions.

Types of API

There are so many types of APIs. Below are several of them:

By use case:

  • Open APIs: publicly available APIs that anyone can use to access a company’s data
  • Internal APIs: APIs used within a company/organization to communicate information between internal apps
  • Partner APIs: APIs designed specifically for third-party developers/partners, and are more limited in access

By protocols:

  • REST API: a widely used architecture for building web services using HTTP methods like GET, POST, PUT, and DELETE format to interact with data resources. REST APIs typically return data in JSON or XML format
  • SOAP API: a messaging protocol used to exchange structured data between web services. SOAP APIs use the XML format for data exchange, and they typically require more bandwidth and processing power than REST APIs. SOAP APIs support more advanced features like transaction, security, and reliability
  • GraphQL API: a query language for APIs that was developed by Facebook. GraphQL APIs allow developers to retrieve only the data they need, using a single query. This can result in more efficient data retrieval and reduced network traffic. Learn more about GraphQL testing.
  • Webhook API: a way to send real-time data from one application to another. Webhook APIs use a simple HTTP POST request to send data to a URL specified by the recipient application. The recipient application can then take action on the data in real-time. Webhook APIs are often used for event-driven applications, such as chatbots or notification systems.

10 API Examples of Popular Apps

1. Twitter API

Twitter offers a wide variety of APIs that developers can use to build applications that interact with Twitter. As one of the most popular social media platforms, Twitter is a great destination for businesses wanting to advertise their products and services. Twitter's Ads API provides businesses with a way to create and manage their advertising campaigns on the Twitter platform. With this API, businesses can create and customize their ads, target specific audiences, and track the performance of their campaigns in real-time.

For example, social media marketing management tools like Buffer allows users to schedule their Twitter marketing calendar, and they must use Twitter APIs to extract analytics from Twitter for their users. Below is the Buffer dashboard with important Twitter metrics such as tweets, replies, retweets, clicks, and more.

Twitter API example for social media management tool Buffer

Source: Backlinko

Another interesting API is the Twitter Direct Message API. With the Twitter Direct Message API, developers can create chatbots that can automatically respond to DMs, providing information, answering questions, or carrying out other tasks. For example, a company can use a chatbot to provide customer support through Twitter DMs, allowing users to quickly get help with their questions or issues.


2. ChatGPT API

What sets ChatGPT apart from other chatbots is its ability to engage in highly realistic, human-like conversations. Unlike traditional chatbots, which rely on pre-programmed responses and scripted dialogue, ChatGPT uses advanced natural language processing and machine learning algorithms to learn and adapt to each user's unique style and preferences.


The most common usage of ChatGPT API is transforming it into a highly customizable chatbot for organizations. ChatGPT will be integrated into the chatbot platform the company is using, or even embedded on the website itself. The language model can be trained to answer highly specific questions on the company’s products and services. Here is a guide to build an AI Chatbot with ChatGPT API with Python.

There have been many emerging AI-powered Content Writing assistants powered by ChatGPT like this plugin for Wordpress, which leverages the ChatGPT API to bring the chatbot’s powerful functionalities onto your Wordpress backend, allowing you to create content within a few seconds.

AI Writing Assistant powered by ChatGPT API on Wordpress

3. Google Map API

The Google Maps API is a web-based service provided by Google that allows developers to embed maps into their web pages or applications. To use the Google Maps API, developers need to authenticate themselves by obtaining an API key. This key is unique to each developer and is used to track usage and ensure that the service is not abused.

Developers can then embed a map into their web page or application using the Google Maps JavaScript API. This API allows developers to customize the map's appearance and functionality, including markers, infowindows, and overlays. Users can freely interact with the map straight on the website, finding the location of their favorite service without having to open Google Maps elsewhere.

Some of the most popular use cases of the Google Map API is providing location-based services. If your online business involves delivering products or providing services at customers' locations, you can leverage the Google Maps API to track shipments or service providers in real-time. This allows your customers to monitor the progress of their delivery or service and estimate arrival times accurately.. 

Address Verification with Google Map API for Pizza shops

For example, here is an Address Verification window at a local pizza shop. As you type in your address and click Find Me, the address will be sent to Google Map via the Google Map API. Google Map will return the exact location for the pizza shop so that the delivery driver knows where to bring the pizzas to.


4. Discord API

Discord API example for gamers

Discord is a free communication platform designed for gamers. It allows users to create and join "servers," which are essentially group chat channels for specific topics or games. With the Discord API, developers can create bots or add extra features to their app using data and services provided by Discord. In simpler terms, the Discord API is a way for developers to interact with Discord using code. REST is one way that developers can use to interact with the Discord API.

Using Discord's REST API, developers can retrieve data about users, such as their profile photos and usernames, by sending HTTP requests to a specific endpoint. This data can be used in external applications or within a Discord application. Essentially, the REST API acts as a bridge between the Discord server and external applications, allowing developers to access and use Discord data in their own applications.


5. GitHub API

GitHub API for developers

GitHub API is a set of tools that allows developers to interact with GitHub programmatically. This means that developers can use code to perform various tasks on GitHub, such as creating, reading, updating, and deleting repositories, files, and issues. It provides an efficient and standardized way for developers to access and manage data on GitHub. Instead of having to manually perform actions on the website, developers can use the API to automate tasks and integrate GitHub with other tools and services. 

For example, a developer could use the GitHub API to automatically create a new repository and add collaborators whenever a new project is created in their project management tool. This saves time and reduces the risk of errors that can occur when manually performing these tasks.


6. PayPal API

Paypal is one of the most popular payment service providers, and its API not only simplifies the payment process but also makes transactions extra secure.

You’ll be able to find Paypal checkout portal on almost any popular eCommerce website. Simply click on the Paypal Checkout button and you’ll be redirected to PayPal, where you can complete the transaction immediately. Your debit/credit card information is registered with Paypal, but Paypal doesn’t share this information through their API, so you can rest assured that your financial safety is guaranteed. This is why Paypal API is so favored by web developers on eCommerce sites.

PayPal API for Checkout

7. eCommerce API

Shopify is an eCommerce platform that allows small businesses to create and manage their online stores with ease. However, sometimes businesses do require custom solutions that go beyond what Shopify provides. This is where Shopify APIs come in.

eCommerce API with Shopify

Developers can use the APIs to build custom storefronts, add new features and functionality, integrate with third-party apps, payment gateways, and shipping providers, as well as automate various aspects of the eCommerce process. 

For example, a developer could use the Shopify API to build a custom storefront that integrates with a third-party inventory management system, allowing businesses to manage their inventory and orders more efficiently. Alternatively, a developer could use the API to create a custom payment gateway that integrates with a specific payment provider that is not natively supported by Shopify. With such an API, Shopify expands their customization capabilities, reaching a much wider customer base.

8. YouTube API

YouTube API Example for developers

YouTube offers an API for any developers wanting to interact with the videos on their platform. The most popular use case is video integration. YouTube API allows you to embed a video straight on your platform. For example, a news website could use the YouTube API to embed videos related to a particular news story, or a fitness app could use the API to add workout videos to its library. The YouTube API allows developers to customize the video player's size, playback quality, and other settings to match their application's design and functionality.

Not just that, you can even leverage the YouTube API for data analysis. Developers can extract data about videos, channels, and playlists, such as view counts, likes, comments, and subscribers. This data can be used to perform analytics, generate reports, and inform content strategy. For example, there is a huge dataset on Kaggle called YouTube Faces With Facial Keypoints containing celebrities facial feature data. This 17GB dataset can be used for facial recognition analysis. 


9. Instagram API

Instagram API is similar to Twitter API, which allows businesses and shop owners to expand its native capabilities as a social media platformShop owners may want to connect their Instagram feeds with their website so users can have a more holistic view of their shop. Visitors can view the comments and interactions on the Instagram posts, which would have been impossible without the Instagram API. 

Likewise, visitors on the Instagram page can purchase the products they want directly from Instagram. The order data will be transferred to the website backend for order fulfillment. 

10. Slack API

Slack API Example

Slack is a cloud-based communication and collaboration platform that enables teams to communicate effectively and work together remotely. From a technical perspective, the Slack API is quite similar to the Discord API as developers can use Slack API to build custom bots that can automate repetitive tasks or provide specific information to Slack users. For example, a team can build a bot that fetches weather information for a specific location or a bot that sends reminders for upcoming deadlines.

Another cool thing to do with Slack API is enabling cross-platform messages to Microsoft Teams. If your team uses both platforms, you can use the Slack API to send and receive DMs and channel messages cross-platform. You can create a Slackbot to automate anything you want yourself: make a document, find an email address, or start a call.

What is API Testing?

APIs are the backbone of digital interactions. However, APIs don’t always work correctly. In such a complicated ecosystem, APIs may fail, retrieving the wrong data, losing data, corrupting data, or worse, leading to system failure. It is when developers need API testing to prevent such issues from happening. 

If you have an upcoming software interview, you need to know how to do API testing. Below is a quick guide to API testing:

  1. Identify the API endpoints: these are the URLs through which your application communicates with the API.
  2. Determine the API method and parameters: API method includes GET, POST, PUT, DELETE and the parameters (query parameters, path parameters, header parameters, and body parameters)  required for the API call.
  3. Create test cases: Create test cases that cover different scenarios, such as valid input, invalid input, and edge cases. You can either use Selenium to test it (which requires Java skills or a low-code automation testing tool like Katalon)
  4. Set up the test environment
  5. Execute the test cases

Why Katalon For API Testing?

Katalon is an all-in-one test automation platform that can perform API testing for teams of any scale, at any engineering expertise. Katalon makes it easy to create and run automated tests for your API thanks to the low-code features. It has keyword libraries that simplify the test creation process. 

For example, you want to test the response status code of a GET request to an API endpoint. Simply create a new test case in Katalon Studio from the New toolbar.


Next, name your test case. Here we’ll name it “API Testing”.

Name your test case for API testing in Katalon

On the top bar you should see a list of Quick Start icons. Click on the “New draft REST Request” to make a REST API Request.

Make REST Request for API testing in Katalon

Here you can select the request method from the drop down list. On the right side will be where the response status is displayed. We’ll choose the GET method.


Select GET method in Katalon

Next, simple type in your API endpoint URL and hit the Run button.

Type in URL endpoint of and press the RUN button

Within a few seconds, you have received your Response status of 200, with detailed information on request time, size, and verification script. You now have your API test case without having to write any code! And this can be scaled to test hundreds of APIs.

Result screen of API testing

As a top-teir API testing tool, Katalon is built to work with modern frameworks and requires minimal maintenance. Katalon supports all types of REST, SOAP/1.1 and SOAP/1.2 requests and can efficiently perform sustainable and productive testing through the use of data-driven testing techniques for increased test coverage and dependability. And Katalon supports more than just API testing - you can do web, mobile, desktop, and visual testing with Katalon, all in 1 place, across a wide variety of environment!

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