Some widely used functionality testing tools include,
Selenium – Open-source, most well-known testing framework used for functional testing automation for browser-based web applications. It supports variety of programming languages for writing test scripts such as PHP, Java, C#, Groovy, Python, Ruby, and Perl. It also supports multiple browsers across OS platforms.
Ranorex Studio – Built with Selenium web driver, it’s used for functional test automation for web, desktop and mobile applications. It supports GUI (Graphical User Interface) and offers record and play back for naïve testers.
UFT – formerly known as QuickTestProfessional(QTP), by HP. Used to perform automated regression testing as well as functional testing. It offers a full-length feature set for API, web services, and GUI testing of desktop, web, and mobile applications across platforms. It is well known for its user friendliness, image-based object recognition feature, reusable test components, and automated documentation.
Katalon studio – The software is built on top of the open-source automation frameworks like Selenium, Appium with a specialized IDE acting as a one stop shop for all API, WebUI, Desktop and Mobile testing and the combined capabilities among those.