To set up a Selenium Grid for cross-browser testing, you need to set up physical or virtual machines with different browsers and operating systems. This requires an investment in the required hardware, software, and support to run the test lab. You also need to put in effort to keep this infrastructure updated with the latest versions and patches. Not everybody can afford these costs and the effort.
Instead of investing and setting up a cross-browser test lab, you can easily outsource a virtual test lab to a third-party cloud provider for cross-browser testing. The Sauce Labs and BrowserStack are leading cloud-based cross-browser testing cloud providers. Both of these have support for over 400 different browser and operating system configurations, including mobile and tablet devices, and support running Selenium WebDriver tests...