Launching a website without thorough cross-browser testing can lead to issues such as high bounce rates on mobile devices due to poor element alignment and compatibility. A comprehensive cross-browser testing checklist is essential to ensure that a site functions properly across different platforms, operating systems, and browsers. Key areas to test include element alignment, SSL verification, font rendering, media compatibility, API connectivity, and code validation. Utilizing tools like LambdaTest, which offers features like the LambdaTest Tunnel for testing locally hosted websites, can aid in identifying issues before going live. Automating repetitive tasks with an online Selenium grid further enhances testing efficiency. Following this checklist helps prevent user experience issues and ensures a smooth website launch.