How to Test API? | Essential Concepts and Explanation

In this FAQ post, we will lay down theories related to the question "how to test API" and what is important to one's testing processes.

What is API Testing?

API testing is a way of ensuring that the application works correctly. It's part of the acceptance testing process, and it involves running tests against a live API to make sure it functions properly. An API, or application programming interface (API), is a set of definitions, specifications, and guidelines for interaction with an application. 

API testing is the process of testing an API to ensure it's performing as expected and in a reasonable amount of time. This can be done manually, but it's also possible to automate the entire process.

The most common way to do this is with API testing tools such as Postman or Swagger Inspector. These tools provide auto-generated documentation and test cases so that developers don't have to write them themselves (and if they need help, there are hundreds available on the web).

An API can be used by developers to build software applications based on existing functionality within another system or service offered by another company — like Facebook's Graph API which allows third-party developers (like us!) access to millions of user profiles. 

APIs are usually created by third-party developers who have special access to applications; they're not published like documentation (which we'll talk about later). If you want to read the code behind an API, you'll need access to the source code so that nobody else can see what you're doing—this makes them private APIs.

If you're interested in writing code that interacts directly with an application's API, it's important to know how the protocols work and what they look like. This can help you avoid errors when designing your applications by making sure they work properly before they're released into the wild. There are different types of APIs, and each one requires a different testing approach:

  • Public APIs: These are the most common type of API, and they can be used by anyone who wants to access them. In general, you should test these APIs with realistic data that your users will use—for example, if you have an API that allows people to order pizza online, then you should test it by asking someone who doesn't work at your company (but is interested in pizza) what they'd like on their next order.
  • Private ones: Private APIs don't allow public access like public ones do; instead they're only available to developers who have signed up for access via an application programming interface (API). For example Uber uses private APIs so its drivers can get paid when they accept rides from new passengers; some banks use private APIs so their customers can check their balances online or make payments through apps like Venmo or PayPal's mobile app Wallet.

What are the benefits of API testing?

The most obvious benefit of API testing is that it allows you to test your APIs against different scenarios and environments in a way that would be difficult or impossible otherwise. For example, if you were only able to run your tests against one particular version of an API—or even worse, just one browser version—you wouldn't know if there were any bugs in those specific versions until after launch day when everyone started using the product! By running tests against multiple browsers and operating systems (including mobile), however, these issues will show up immediately because they're already present on people's devices before anything else happens during the development period between planning out the release cycle for something new coming out later down the road.

How to Test API

Use a selenium plugin for your system.

Selenium is a suite of automated software tools for web testing. It can be used to test your API, mobile apps, and desktop applications.

There are many ways to install this software on your system:

  • Run from the command line using the selenium-server tool.
  • Install it using pip or conda (note that you'll need Python installed).

Use a browser extension like chrome driver or Socket Stream.

ChromeDriver is a tool that allows you to test your API. ChromeDriver is a Chrome extension that allows you to test your API. It gives you access to all of the same functionality as the command line tools and can also be used with Socket Stream.

Test using Postman.

It is a tool for testing APIs, so you can use it to test your APIs as well. It's easy and fun to use, and it makes sure that everything works properly before moving on to other parts of the process. When you're ready to make changes or additions, there are plenty of resources available online for help with those tasks (like this article).

Test using curl or wget tools.

Curl or wget are the best tools to use if you want to test your API's response.

  • If you're testing a tool that uses curl or another HTTP client, it can be easier than using a command-line interface (CLI). The latter requires knowing how to use the terminal, which might not be necessary if there's another way of doing it.
  • curl is available on almost all platforms, making it easy for anyone who has access to internet services without having any additional software installed on their computer (like coding languages). It also allows users who don't have much experience with command line interfaces to learn more about these types of software by using them themselves rather than just explaining them from scratch before getting started with an actual project.

Use a Library:

You don't have to reinvent the wheel. You can use a library to test your API from the command line. You can also use a library to test your API from the command line with a single command. The simplest way is to write an HTTP client that uses curl or wget and then run it against your server. This approach works well for simple APIs, but it does not scale well as your code base grows larger and more complex. As you add more features, more tests will be required for users and developers to be confident in their ability to use them correctly—and this means increasing the complexity of testing infrastructure alongside those features being added. To test API, one can go for a manual approach or an automated approach.

Manual API Testing:

Manual API tests are a great way to test your application because they allow you to use different browsers and operating systems, which makes it possible for everyone who wants to try out something new with their favorite browser or device type. Manual API covers testing of basic functionality, basic errors, bugs, basic, vulnerabilities, and performance issues (performance is a very important aspect of any application).

Automated API Testing:

They are a form of automated software testing. They’re run against an application or API to determine how well it behaves when exposed to different inputs and conditions.

What do you need to start API testing?

  • A computer. You'll need to be able to access the site, but not necessarily run it locally on your machine.
  • A browser. You'll need something that can display web pages and interact with them (like Chrome or Firefox). This can be either a desktop version of these browsers or a mobile app installed on both Android and iOS devices.
  • The network connection between your computer and the server you're testing against; could be an ethernet cable connecting directly from your laptop's Ethernet port into an outlet in the wall, as well as using Wi-Fi if available at all times (if not then it could be done through another device connected via Bluetooth).
  • An API test script that runs alongside all other software programs inside another container within containers running inside get the idea.


To conclude the question "how to test API", we can state that they can be tested in many ways. Selenium is a popular open-source web testing tool. You can use it to test your API, and it will help you check if you're dealing with any issues. ChromeDriver and Socket Stream are browser extension tools that give you access to the same functionality as Selenium but in a much more user-friendly way. They can be used for testing any website or application on your system, including APIs. Postman is an application that allows you to send requests from within the program itself—that means no need for extra software like curl or wget tools.

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