On macOS, the most popular web browsers, and the ones I use most frequently, are Chrome, Firefox, and Safari. My tool of choice to test these browsers is Little Snitch. The quietest of the three web browsers appears to be Safari. It’s important to note, however, that Chrome and Firefox are self-contained, whereas Safari is part of macOS and can delegate some of its functionality such as iCloud sync to other macOS processes, many of which phone home to Apple. I personally don’t use sync or sign-in with any web browser, so I have no desire for any of them...