The Essentials Of API Testing

The Essentials Of API Testing

While at first glance the words “API testing” might make you think that you will need to learn a completely new branch of testing that isn’t the case. I assure you that if you already have good QA testing foundations then you are ready to test API as well. And it all comes down to the fact that API is just a specific kind of software.


What is API testing?

To answer what is API testing we need to understand what APIs are in the first place. API stands for “Application Programming Interface” and refers to mechanisms and code that allow two distinct applications to communicate with each other. For example, allowing your phone’s Maps app to tap in on the existing web browser Google Maps infrastructure.

So API testing is in short just the practice of doing Quality Assurance specifically on API products, to ensure the connectivity works as intended.

When do we need API testing?

You will need to do an API test if you run into a bug tied to the connection between two different software. If your API software for example fails to update its date, then that’s a bug on an specific software, not on the API. But if the user end software is unable to update the information from the other software, then it is time to bring out the API testing tools.

Responsibilities of an API tester

As an API tester, it’ll be your job to confirm that two different applications seamlessly communicate with each other as intended. And while this might seem harder than other types of testing it’s honestly more or less in the same line.

When testing APi or any other kind of software it’s important to remember that you are first and foremost responsible for identifying and cataloging bugs and other issues, not solving them on your own. So an API test is not that any different from testing other programs, it just has more variables since ultimately there’ll be three sets of code working together, or even more depending on the specific API for testing.

Understanding API testing tools

Now that we have covered the facts on API testing we must take a closer look at API testing tools to illustrate how to best approach the task at hand.

The good news for any upcoming API tester is that API applications are so integral in today’s landscape that there’s no shortage of software designed to test API and help you streamline your work through automated tools and aids. In fact, there are so many alternatives that you might have a hard time knowing where to look.

The following are some of the most popular API test kits in the market, but keep in mind that they are far from being the only options available for you:

  • Katalon
  • Rest-Assured
  • apigee
  • JMeter
  • Postman
  • SoapUI
  • API Fortress

Of course, no team will use every single testing tool in one project, and sadly there’s no such thing as a single API master test kit, so that means you’ll have to choose one software suite and stick with it for the most part. But how can you do that?

Given the sheer volume of alternatives trying out every single test kit is also unfeasible, so in that sense, you’ll need to look at what each environment offers and even more importantly keep in mind what you as a tester need.

Keep in mind the complexity of the software, as something too elaborate or too technical for other team members to understand might prove counterintuitive in the long run. Interconnectivity is also a major benefit with testing tools, as any software that can interact with existing applications on your workflow like Jira will be much, much easier to use. And of course, check reviews and investigate thoroughly. There’s no better way to know what’s the best fit for your needs than by comparing multiple available options.

Is there an API master test kit?

Unfortunately, there is no such thing as an API master test kit for a wide variety of reasons. First and foremost the simple fact is that API testing software is being designed and commercialized by multiple companies, and with constant competition every company will release its version for different needs and budgets.

Also, it is undeniable that every company wants their API solution to be the main tool for developers, so in a sense, most API test kits you’ll run into are already trying to be a “master test kit”

So in short while there’s no overall best API test software, they are all aiming to be the best possible standalone solution for your needs.

The most common API testing interview questions

As an API tester, you are by definition a QA tester as well, and that means that a lot of API testing interview questions will be the same as any other interview. However, we’ll be listing some that are more unique to the world of API so you have a good idea of how to approach your next interview.

  • What’s the difference between API and Web Services?
  • What are some common architectural styles for creating API?
  • What is the test environment of API?
  • What are the most common API testing types?


For the most part, yes. The methodology might vary, but at the end of the day, your responsibilities and approach are the same.

Your choice of API testing software not only comes from your personal preferences but also what your company might demand or have at the time. So it’s ideal to be adaptable when it comes to tools.

Definitely. API is used for countless applications and most systems online will involve API to some degree, so there’s a large market for API testers.

Understanding the intricacies of API and its role in web development goes a long way. And of course, results as always do matter.

The bottom line

While API testing might seem intimidating at first, it ultimately is just another category of software testing. And that means that as long as you keep your fundamentals and have the right tools it’ll be as easy as any other project. So if you are looking to get started on the world of QA testing or are interested in remaining up to date on it, make sure to come back to Test Pro and check our courses and blog regularly.

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