--- description: Apart from Functional testing, non – functional requirements like performance , usability ,load factor are also important.How many times have you seen such long load time messages while accessing an application title: Non Functional Testing image: https://www.guru99.com/images/non-functional-testing-1.png --- [Skip to content](#main) **⚑ Smart Summary** Non Functional Testing validates how a software application performs in terms of reliability, usability, security, scalability, and other quality attributes. This walkthrough explains objectives, parameters, characteristics, common testing types, and practical example test cases used by quality assurance teams. * 🎯 **Quality Focus:** Non-functional testing measures how a system performs rather than what it does. * πŸ“ **Measurable Criteria:** Every requirement is quantified, eliminating subjective wording such as good, better, or best. * πŸ” **Critical Parameters:** Security, reliability, scalability, usability, and portability dominate non-functional verification. * πŸ§ͺ **Diverse Test Types:** Performance, load, stress, recovery, and compatibility testing each address specific quality risks. * πŸ“Š **Business Impact:** Strong non-functional testing reduces production cost, downtime, and customer dissatisfaction across releases. [ Read More ](javascript:void%280%29;) ![Non Functional Testing]() ## What is Non-Functional Testing? **Non-Functional Testing** is a category of software testing that validates the non-functional aspects of an application β€” performance, usability, reliability, and similar quality attributes. It evaluates the readiness of the system against criteria that functional testing never addresses, ensuring the application meets enterprise expectations under real-world conditions. A classic example of non-functional testing is measuring how many concurrent users can log in to an application without performance degradation. Non-functional testing is as critical as functional testing because it directly affects client satisfaction and overall product perception. [](https://www.guru99.com/images/1/022218%5F1114%5FWhatisNonFu2.png) ## Objectives of Non-Functional Testing Non-functional testing is performed to improve the overall quality and longevity of a product. The key objectives include: * Increase usability, efficiency, maintainability, and portability of the product. * Reduce production risk and the cost associated with non-functional defects. * Optimize the way the product is installed, set up, executed, managed, and monitored. * Collect measurements and metrics for internal research and development. * Improve understanding of the product’s behavior and the technologies in use. ## Characteristics of Non-Functional Testing The following traits define how non-functional testing should be planned and executed: * It must be measurable, leaving no room for subjective descriptions such as good, better, or best. * Exact numbers are usually unknown at the start of the requirements process. * Requirements must be prioritized so the highest-risk areas are addressed first. * Quality attributes are identified accurately during the software engineering phase. ## Non-Functional Testing Parameters Eleven parameters are typically used to scope non-functional testing efforts: 1. **Security:** Measures how a system is safeguarded against deliberate and accidental attacks from internal or external sources. Verified through Security Testing. 2. **Reliability:** The extent to which a system continuously performs its specified functions without failure. Verified through Reliability Testing. 3. **Survivability:** Confirms that the system continues to function and recovers itself after a failure. Verified through Recovery Testing. 4. **Availability:** Determines the degree to which a user can depend on the system during operation. Verified through Stability Testing. 5. **Usability:** The ease with which users can learn, operate, prepare inputs, and consume outputs from the system. Verified through Usability Testing. 6. **Scalability:** The degree to which a software application can expand its processing capacity to meet rising demand. Verified through Scalability Testing. 7. **Interoperability:** Checks how a software system interfaces with other software systems. Verified through Interoperability Testing. 8. **Efficiency:** The extent to which the system handles capacity, quantity, and response time under load. 9. **Flexibility:** The ease with which the application can work across different hardware and software configurations, such as varying RAM or CPU specifications. 10. **Portability:** The flexibility of the software to move from its current hardware or software environment to another. 11. **Reusability:** Refers to the portion of a software system that can be adapted for use in another application. [](https://www.guru99.com/images/1-2015/012715%5F0453%5FNonFunction4.png) ## Type of Software Testing Software testing is broadly classified into three categories: * **Functional Testing** * **Non-Functional Testing** * **Maintenance Testing** Each category contains multiple testing levels, which teams often refer to as testing types. Different books and reference materials may classify them slightly differently, so expect minor variations. The list of testing types is not exhaustive β€” over 100 distinct testing types exist, and new ones continue to emerge. Not every type applies to every project; the scope depends on the nature, risk profile, and complexity of the application under test. ### RELATED ARTICLES * [Software Testing Life Cycle (STLC) ](https://www.guru99.com/software-testing-life-cycle.html "Software Testing Life Cycle (STLC)") * [Sanity Testing vs. Smoke Testing: Key Differences, Examples & When to Use Each ](https://www.guru99.com/smoke-sanity-testing.html "Sanity Testing vs. Smoke Testing: Key Differences, Examples & When to Use Each") * [Test Strategy Document Example (Sample Template) ](https://www.guru99.com/test-strategy-document-in-software-testing.html "Test Strategy Document Example (Sample Template)") * [Stability Testing in Software Testing ](https://www.guru99.com/stability-testing.html "Stability Testing in Software Testing") ## Types of Non-Functional Testing The most common types of non-functional testing performed by QA teams include: * Performance Testing * Load Testing * Failover Testing * Compatibility Testing * Usability Testing * Stress Testing * Maintainability Testing * Scalability Testing * Volume Testing * Security Testing * Disaster Recovery Testing * Compliance Testing * Portability Testing * Efficiency Testing * Reliability Testing * Baseline Testing * Endurance Testing * Documentation Testing * Recovery Testing * Internationalization Testing ## Example Test Cases for Non-Functional Testing The following examples illustrate how non-functional test cases are written in real projects: | Test Case # | Test Case | Domain | | ----------- | ------------------------------------------------------------------------------------------------- | --------------------- | | 1 | Application load time should not exceed 5 seconds when up to 1000 users access it simultaneously. | Performance Testing | | 2 | Software should be installable on all supported versions of Windows and macOS. | Compatibility Testing | | 3 | All web images should include descriptive alt tags. | Accessibility Testing | ## FAQs βš–οΈ What is the difference between functional and non-functional testing? Functional testing verifies what the system does against specified requirements. Non-functional testing measures how the system performs, including speed, reliability, usability, and security, ensuring the application meets quality standards beyond core feature behavior. πŸ› οΈ Which tools are commonly used for non-functional testing? Popular tools include JMeter and LoadRunner for performance, Selenium for usability automation, Burp Suite and OWASP ZAP for security, and BrowserStack for compatibility. Each tool targets a specific non-functional area that QA teams want to measure. πŸ“… When should non-functional testing be performed? Non-functional testing should start once the system is functionally stable and before major releases. Performance, security, and reliability tests are usually scheduled in late testing phases, but shift-left strategies promote earlier execution alongside development. πŸ“ˆ How is non-functional testing measured? Each parameter is measured against quantifiable thresholds. Performance is measured in response time and throughput, security through vulnerability counts, usability through task completion rates, and reliability through mean time between failures. Numbers replace subjective opinions. πŸ’Ό Is non-functional testing manual or automated? Both. Performance, load, stress, and security testing rely heavily on automation due to scale and repeatability. Usability and accessibility testing often require manual observation, expert reviews, or assistive-technology checks alongside automated tooling. πŸ€– How is AI changing non-functional testing? AI generates load profiles, predicts performance bottlenecks, prioritizes risky test cases, and analyzes log data automatically. AI-driven platforms reduce execution time and surface regressions faster, helping QA teams scale non-functional coverage across releases. 🧠 Can AI fully automate security and performance testing? No. AI accelerates scans, baseline creation, and anomaly detection, but expert testers still interpret results, validate exploit chains, and design test scenarios. AI augments human judgment in non-functional testing rather than replacing experienced QA engineers. #### Summarize this post with: ChatGPT Perplexity Grok Google AI **Stay Updated on AI** **Get Weekly AI Skills, Trends, Actionable Advice.** ##### Sign up for the newsletter Subscribe for Free You have successfully subscribed. 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