Non Functional Testing - A Detailed Overview

Non Functional Testing – A Detailed Overview

Imagine you’re driving a car with the engine roaring, the wheels spinning, and the wind blowing through your hair. Everything might seem perfect until you step on the brakes, and it takes 10 full seconds to bring the car to a stop. Conducting thorough testing can help detect such flaws.

Non-functional testing, here, will help test the braking system’s response time, how well it works, how effective it is, its performance, and so on.

Similarly, non-functional testing of a software helps understand how well the product works. It is the process of testing a product to evaluate its performance, reliability, usability, and other aspects that are not directly related to its functionality. It is like putting your car through a rigorous set of tests to ensure that it handles all expected and unexpected situations well.

In this blog, we will explore non-functional testing and its different types.

What is Non Functional Testing?

Non-functional testing is a software testing type that tests the non-functional aspects of an application, such as usability, performance, scalability, reliability, security, compatibility, and more. In contrast, functional testing focuses on testing its functional behavior.

Simply put, non-functional testing checks the product’s quality rather than its features. You need to understand the impact that non-functional testing has on a product. In the world of software development, non-functional testing is as necessary as functional testing. Without it, a system may work perfectly fine in a controlled environment but may fail spectacularly in the real world.

Non Functional Testing Example

Let’s take an e-commerce website as an example to understand how non-functional testing plays a vital role in product quality.

The website works well on normal days. But how should the website prepare for a sale day? To ensure this, the QA team will have to estimate the maximum number of people expected to visit the website in one day.

Also, they would have to estimate the average visits expected in a day. Then the website will be tested for a maximum and average load. The website should have to work well at the highest expected load, and the website should continue functioning if it is subjected to an average load over the period of the sale.

Characteristics of Non Functional Testing

The key characteristics of non-functional testing are as follows,

  • Non-functional testing has to be quantifiable. Hence using subjective terms like “good,” “better,” “best,” etc., will not be suitable for this type of testing.
  • It may not be possible to determine the precise figures at the beginning of the requirement process.
  • Prioritizing the requirements is highly important.

Objectives of Non Functional Testing

Some of the objectives of non-functional testing are,

  • To improve the performance, usability, portability, efficiency, and/or security of the product.
  • To help minimize the cost related to the non-functional aspects of the application.
  • To reduce the production risk associated with the non-functional aspects.
  • To improve the understanding of the product’s behavior and technologies used.

Non Functional Testing Parameters

Non-functional testing parameters typically include the following parameters, as shown in the image below,

Non Functional Testing Parameters

Let’s discuss some of these parameters in detail below.

1. Security

This parameter defines how a system is protected against planned and unplanned attacks from internal and external sources. This can be tested via Security Testing.

2. Reliability

This parameter tests the ability of a system to consistently perform its intended functions without failure for a specific period of time. This can be tested via Reliability Testing

3. Survivability

This parameter defines the ability of a product to continue functioning and recover itself in the event of any failure or disruption. This can be tested by Recovery Testing

4. Availability

It determines the extent to which a user can rely on the availability of the system and its functionalities during its operation. Stability Testing measures this parameter.

5. Usability

It refers to the level of ease with which a user can interact with a product in terms of learning, operating, and preparing inputs and outputs. This aspect is evaluated via Usability Testing.

6. Scalability

It determines the ability of a system to scale up or down based on the workload without affecting performance. This can be tested via Scalability Testing.

7. Interoperability

This parameter defines the ability of a system to interface with other software systems. This can be checked by Interoperability Testing.

8. Efficiency

It identifies the degree to which a software system can handle quantity, capacity, and response time.

9. Flexibility

Flexibility determines the application’s ability to work seamlessly across various hardware and software configurations. For example, most applications would require minimum RAM and CPU requirements to work.

10. Portability

It defines how easily an application can migrate from one hardware or software environment to another.

11. Reusability

It refers to a part of the software system that can be reused in another application.

Type of Non Functional Testing

There are several types of non functional testing, including,

  • Performance Testing
  • Compatibility Testing
  • Load Testing
  • Usability Testing
  • Failover Testing
  • Stress Testing
  • Scalability Testing
  • Maintainability Testing
  • Volume Testing
  • Recovery Testing
  • Security Testing
  • Portability Testing
  • Compliance Testing
  • Efficiency Testing
  • Endurance Testing
  • Reliability Testing
  • Visual Testing
  • Internationalization Testing
  • Localization Testing

Now that you know there are plenty of non-functional testing types, let’s discuss some of the non-functional testing types in detail below,

1. Performance Testing

Performance Testing tests how well the software works. It helps to identify and eliminate performance-related issues of the product. It checks various aspects of software quality, like validating if it’s fast, stable, scalable, and reliable.

But prior to this test, the expected result should be defined. If not, it might be difficult to determine if the test was a success or failure.


The product’s loading time should not exceed 5 seconds when 5000 users use it simultaneously.

Tools Preferred:

  • Apache JMeter
  • LoadNinja
  • Headspin

2. Load Testing

Load testing determines the loading capacity of the website or application. That is, the number of concurrent users a system can handle at one time. It helps test if the product is working as expected under normal and heavy loads.


  • Check that the mail server can handle thousands of concurrent users.
  • Testing an e-commerce application by simulating thousands of users making purchases simultaneously.

Tools Preferred:

  • Neotys Neoload
  • JMeter
  • Parasoft Load Test

3. Security Testing

Security testing identifies the application’s ability to protect data against security threats and prevent unauthorized access. It helps identify the security weaknesses in the system.

This testing can be done by looking into the system from an attacker’s perspective. Also, you need to identify the parts of the code that an attacker will most likely attack. By doing so, you can create robust products.

Example: Performing penetration testing on a bank application to identify security vulnerabilities.

Tools Preferred:

  • ImmuniWeb
  • Vega
  • Google Nogotofail

4. Portability Testing

Portability testing helps test if the software can run on different operating systems without any issues. The functionality of the product under the same platform but with different hardware will also be tested.


  • Test if the product can run on iOS and Android operating systems.
  • Test if the application works on Mac, Windows, and Linux platforms.

Tools Preferred:

  • Testsigma
  • BrowserStack
  • Sauce Labs

5. Compatibility Testing

This testing helps verify that the software or system is compatible with other software or systems. That is, checking if the product is compatible with different software, hardware, and network configurations.

Further, it helps make sure that the application is cross-browser compatible and provides a seamless and user-friendly experience across various browsers, devices, platforms, and versions.


Testing if the mobile application is compatible across different operating systems, versions, and devices.

Tools Preferred:

6. Usability Testing

Usability testing identifies if the application is easy to use and accessible for users. Statistics state that 97% of users consider ease of use as the highest quality for mobile applications.


  • Checking if the navigation within the product is clear and easy to use.
  • Verify the design is simple and clutter-free.
  • Check if the logo redirects to the homepage.

Tools Preferred:

  • Maze
  • Optimal Workshop
  • UsabilityHub

8. Reliability Testing

Reliability testing helps test if the application is working correctly under predetermined parameters without causing errors. The product will be tested for a specific period of time in a specified environment to check its reliability.


Check that the web pages load and are interactable when 50 users are using the website.

9. Efficiency Testing

Efficiency testing helps test whether the application works efficiently and satisfies the user and business requirements.

Tools Preferred:

  • WebLOAD
  • JMeter
  • LoadNinja

10. Volume Testing

Volume testing is a type of software testing that helps evaluate the performance and behavior of the software when it is exposed to a large volume of data of database. It is also called flood testing.

This testing helps identify performance issues, such as slow response times, memory leaks, or crashes, that may occur when the system handles high data volumes.


Test the behavior of the music application when thousands of users listen to songs from it.

Tools Preferred:

  • HammerDB
  • NoSQLMap
  • DbFit

11. Recovery Testing

Recovery testing determines how well a product can recover from a crash, network failure, hardware failure, and other unexpected issues. This helps ensure the application can quickly and efficiently return to its normal state after a failure or disruption.

During recovery testing, testers intentionally introduce faults, such as system crashes, network failures, or power outages, to observe how the system responds and recovers. It is also known as disaster recovery testing.


  • Check if the system gets back to a normal state after the network is unavailable and is available after some time again.
  • Check if the system responds to users after a server overload.

12. Responsive Testing

Responsive testing helps ensure that the website or application works properly on different devices, platforms, screen sizes, and resolutions. It is important because people use a wide range of devices to access websites and applications, including smartphones, tablets, laptops, and desktops.

According to reports, 50% of users will not prefer to use a website if it is not mobile-friendly, even if they like the business. That is why it is highly important to test the responsiveness of an application to make sure it adapts to any screen, device, or platform.

Responsive testing identifies issues, such as text being too small, button issues, or layout issues. Testers usually automate responsive testing using automation testing platforms as it saves time, cost, and effort.


  • Check if the button height and width are the same on all devices.
  • Check if the font style is the same as expected on all devices.

Tools Preferred:

  • Testsigma
  • BrowserStack
  • Responsinator

13. Stress Testing

Stress testing helps verifies the stability of software under extreme conditions. Here, testers measure the application’s error-handling capabilities and robustness under heavy load conditions that are beyond its normal operational capacity. This helps identify the breaking point of a system and how well it can handle unexpected or heavy loads.


Picture this scenario: Amazon launches a big festive sale, and the application witnesses a heavy spike in traffic as millions of users access it simultaneously.

Testers will have to test if the e-commerce app can handle millions of users simultaneously for the period of the sale.

Tools Preferred:

  • LoadRunner
  • JMeter
  • Neo load

14. Visual Testing

Visual testing helps find even the minimal bugs or defects in the UI. It is sometimes referred to as visual UI testing. It validates if the user interface appears correctly across various devices, platforms, and versions.

Let’s take an example to understand this better. Typically visual testing usually involves comparing the different visual outputs against the expected design.

Testsigma allows you to automate visual testing. The how-to-do-it part is pretty simple. Make sure to enable the option Enable visual testing for a step while creating your test cases. Alternatively, you can bulk-select the test cases and enable the option.

Enabling Visual Testing

Now, Testsigma will capture screenshots of the application or website and compares them against a base image to detect any visual differences or anomalies in the design.

After successful execution, you’ll find a red or green camera icon under every test case. Green represents that there are no visual differences, whereas red represents that there is a visual difference.

Test to compare visual dfferences

On clicking the red camera icon, you can easily find the visual differences as Testsigma highlights them for easy identification.

visual differences

Example:Verify that the dropdown list appears as expected.

Tools Preferred:

  • Testsigma
  • Percy
  • Kobiton


Non-functional testing is a comprehensive approach that helps ensure that the application is optimized for user experience and meets the necessary quality standards. It helps developers to identify and address potential issues before the application is released to the public. That way, it reduces the risk of failure and ensures that the application meets the user’s expectations.

Testsigma can make your testing effective, fast, and comprehensive. You can quickly automate UI testing, visual testing, and cross-browser testing for web, mobile, and desktop applications in one place. Also, you can quickly automate complex workflows in simple English.

Sign up to Testsigma Cloud for free and test your applications on the cloud.

Frequently Asked Questions

What is functional vs non-functional testing?

Functional testing verifies that the application is working as intended. On the other hand, non-functional testing checks how well the application works in terms of efficiency, performance, security, scalability, reliability, and portability.

What are non-functional testing examples?

Non-functional testing aims at testing the non-functional aspects of the product. To understand it in a better way, take a look at these examples,

  • Verify that the dashboard of the application loads within 5 seconds after login.
  • Check that the email notifications are sent within 3 minutes.
  • Verify that the 500 users can log in to the application simultaneously.

Test automation made easy

Start your smart continuous testing journey today with Testsigma.