Why Is Backend Testing Important?

Backend testing is an integral part of creating a high-quality software product. Moreover, it is a tougher part of the quality control process. While working with the frontend, the tester needs to simulate user interactions with the software. In the backend, on the other hand, the tester needs to check if the elements hidden from users’ eyes work smoothly.

The importance of backend testing is hard to overestimate. Nowadays, data volumes are growing and databases are becoming more and more complex. Even the slightest error in the interaction of internal elements can make software absolutely inoperable. In this article, we will explain why backend testing is important, describe its key aspects, and provide tips on how to do it properly.

What is backend testing?

First, let’s get the basics straight. Each piece of software consists of the following parts:

  • GUI – the visible part of the product.
  • API – receiving requests from the user, processing them, and getting a response from the server.
  • Database – the data storage itself.

Backend testing is a check of the API and the database for any contingencies. To put it simply, backend testing is about eliminating potential errors in all parts of the product that the user can’t see.

Backend database testing always comes down to the following:

  • Testing the internal structure.
  • Testing the correctness of the user interaction with the database.
  • Checking the database for load resistance.

In turn, API testing is a much more complicated concept, and therefore below we will consider it in more detail.

Basics and definition

API (Application Programming Interface) is a set of ready-made classes, procedures, functions, structures, and constants provided by an application (library, service) for use in external software products.

In short, API gives us the possibility to use someone else’s developments for our own purposes. It is a set of functions that can be used by any application running on that operating system. For example, it can use standard functions to draw the interface.

Modern APIs often take the form of web services that provide users (both people and other web services) with some kind of information. Usually, the information exchange procedure and data transfer format are structured so that both parties know how to interact with each other.

Why you should use API testing

Automated API testing is able to clear the software backend from bugs in a minimum amount of time. This in turn will significantly improve the quality of the product, as well as save time and money. In particular, API testing has the following benefits:

  • Earlier Testing
    API testing is about testing the interaction logic. Therefore, there is no need to wait for the entire product to be completed since the tests are isolated and can be performed on separate parts of the product.
  • Faster Resolution
    It’s easier to find defects and resolve them.
  • Speed
    You can run a thousand API tests in just a few minutes. In this case, errors can be fixed immediately.

What are the types of API testing

All kinds of testing that we are used to are applicable to API testing:

  • Functional testing – checking the API for what it’s supposed to do;
  • Load testing – testing the API’s resilience to large numbers of users;
  • Security testing – checking security requirements such as authentication and access control;
  • Usability testing – checking the API for use in different ways;
  • Documentation testing – documentation must guide the user;
  • Reliability testing – the API outputs the results required of it;
  • Proficiency testing – the API must enhance the developers’ abilities;
  • Negative Testing – checking for input errors from the user.

It’s worth noting that due to the nature of the interface, API testing can’t be done manually. It would take too much time. Consequently, for quality testing of API, we need special tools that can speed up the process and thus save the budget and timing of the project. But we will speak about them a bit further in this article.

How to do API testing

API testing has its own specifics, but we can use such generally accepted techniques as:

  • Typical Result Test. Remember that there should be a minimum number of variables in the test.
  • Test for failure. Create test cases for all possible API input combinations and possible loads.
  • Boundary value analysis. In API requests, parameter values can be passed explicitly. This is a great occasion to highlight the boundaries of the input and output values and check them.
  • Partitioning into Equivalence Classes. Even a small API has many use cases and many combinations of input and output variables. Therefore, we can once again use our skills of allocating equivalent classes.

When testing, keep in mind that APIs are largely designed to integrate services. And it is often not people who work with them, but other software systems. Therefore, you need to evaluate the API from the standpoint of its usability by other products and from the standpoint of easy integration with it.

Tools used for API testing

There are many good backend testing tools available today. The best way is to read through the details carefully and choose what suits your business requirements best. We recommend the following backend automation testing tools:

jMeter is a powerful tool that was originally intended for testing web server performance. Now JMeter is actively used for the automation of backend testing work. You can use it to test the performance of web applications, servers, and even databases. The application can simulate a certain number of users and threads visiting a particular web server or application. By creating a simulated load on your web application, JMeter measures its performance. Moreover, you can specify several repetitions with cycles to get an average result, implement a statement, and see the test results graphically and statistically.

SoapUI is a complete API test automation framework for SOAP, REST, and more. It is a cross-platform client window application written in Java. In the paid version of the program, called SoapUI Pro, you’ll be able to do a bit more, such as install plugins using the plugin manager, test data drivers, intercept traffic, evaluate your web services’ coverage with tests, and create reports.

Postman is a complete API test automation framework for SOAP, REST, and more. It has an open-source version as well as a professional version. Postman provides automatic documentation for developers, and it eliminates the problem where developers change functionality and then forget to report it. Getting started testing APIs with Postman is easy. You can create REST, SOAP, and GraphQL requests. The tool supports multiple authorization protocols and certificate management.


We hope that now it is a little clearer to you what backend testing is and why it is necessary. API testing along with automation can significantly reduce app development costs and increase test coverage. After thorough backend testing your product will work smoothly and you won’t need to spend money on its rework.

However, it is worth remembering that for quality backend testing you need professional QA specialists. True masters of their craft won’t leave a chance for any bug or unexpected situation.

October 8, 2021

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