SELENIUM is a free (open-source) automated testing framework used to validate web applications across different browsers and platforms. Its simple scripts to run tests directly within a browser. You can use multiple programming languages like Java, C#, Python, etc to create Selenium Test Scripts.
https://www.selenium.dev/documentation/en/Selenium is a portable framework for testing web applications. Selenium provides a playback tool for authoring functional tests without the need to learn a test scripting language (Selenium IDE). ... The tests can then run against most modern web browsers. Selenium runs on Windows, Linux, and macOS.