It is very difficult for front-end developers for web applications to check if HTML, CSS or javascript codes are working properly for each browser and all versions of these browsers. Likewise, it is not possible for the test team to test for each browser and its versions. For this, there are platforms such as Experitest, BrowserStack, CrossBrowserTesting, SmartBear, Browserling, Saucelabs that enable tests to be run for all desired browsers. You can do your cross-browser tests easily using these platforms.