The non-functional aspects of a system can require considerable effort to test. Within this group it can be found different means of testing, for example, performance testing conducted to evaluate the compliance of a SUT with specified performance requirements. These requirements usually include constraints about the time behavior and resource usage. Performance testing may measure response time with a single user exercising the system or with multiple users exercising the system. Load testing is focused on increasing the load on the system to some stated or implied maximum load, to verify the system can handle the defined system boundaries. Volume testing is often considered synonymous with load testing, yet volume testing focuses on data. Stress testing exercises beyond normal operational capacity to the extent that the system fails, identifying actual boundaries at which the system breaks. The aim of stress testing is to observe how the system fails and where the bottlenecks are.

Security testing tries to ensure the following concepts: confidentiality (protection against the disclosure of information), integrity (ensuring the correctness of the information), authentication (ensuring the identity of the user), authorization (determining that a user is allowed to receive a service or perform an operation), availability (ensuring that the system performs its functionality when required), and non-repudiation (ensuring the denial that an action happened). Authorized attempts for evaluating the security of system infrastructure is often known as penetration testing.

Usability testing focuses on finding user interface problems, which may make the software difficult to use or may cause users to misinterpret the output. Accessibility testing is the technique of making sure that our product is accessibility (the ability to access the system functionality) compliant.