Cross-browser testing ensures web applications function correctly across various browsers and operating systems, but manual testing can be time-consuming due to the numerous browser versions available. Automation testing, using tools like JUnit and Selenium, streamlines this process. JUnit, a unit testing framework for Java, can be integrated with Selenium WebDriver to automate web application testing, allowing for more structured test cases. The article explains the process of setting up JUnit and Selenium for automation, including downloading necessary JAR files, writing test scripts, and utilizing cloud-based testing solutions like LambdaTest to overcome the limitations of local testing environments. LambdaTest's Selenium grid offers over 2000 browser combinations for efficient cross-browser testing, supporting multiple programming languages and enhancing test execution with features like parallel testing and advanced capabilities. The integration of JUnit, Selenium, Maven, and Jenkins provides a robust solution for cloud-based application testing, improving test effectiveness and maintenance.