In order to deliver high quality products, quality assurance constantly assists the development team by running various kinds of tests and providing feedback during both production and maintenance phases. Depending on the product specification, there are features that should be considered, such as functionality, performance, responsiveness, and usability. Functionality testing is executed to ensure the product correctly fulfills its function. Responsiveness testing is essential to guarantee proper display on a broad range of resolutions, browsers and devices. Ease of use is determined by means of usability testing. Performance testing gives us knowledge on how various factors may affect website speed. Each type of test provides priceless information allowing to create valuable products.