Everything, really. The protocol is a layer underneath the WebDriver protocol, and what Chrome DevTools uses. So it's pretty much the most complete API for the

Everything, really. The protocol is a layer underneath the WebDriver protocol, and what Chrome DevTools uses. So it's pretty much the most complete API for the browser; in fact, Chrome is shipping the protocol as the 1st class API for headless Chrome . We use it in Lighthouse [0] to reload the browser, manipulate ServiceWorkers and caches, execute a bunch of tests on pages and measure performance characteristics. I've also used it for automated profiling [1], in case you want to profile your JS with a bit more control. Using this for testing or scraping would work as well, but you might as well move a layer up and use WebDriver as the commands will be fairly common. [0] https://github.com/GoogleChrome/lighthouse/ https://github.com/GoogleChrome/lighthouse/ [1] https://github.com/paulirish/automated-chrome-profiling/ https://github.com/paulirish/automated-chrome-profiling/