 Hey there, I'm Kase, and here's what's new in DevTools in Chrome 59. First up is the Coverage tab. The Coverage tab shows you what CSS and JavaScript the page is using. Let's see how to use this to speed up page load time. Open the command menu with Command Shift P on Mac or Control Shift P for Windows and Linux. Type coverage and select show coverage. The Coverage tab opens up at the bottom of the DevTools window. Click Reload page, wait a little bit for the page to load, and then click Stop Recording. You can see there's a bunch of external files getting loaded, and most of the bytes in those files aren't even getting used. Click on a URL to see a line-by-line breakdown for that file. So to speed up page load time, I could inline the use code into the page's HTML and asynchronously load the unused code. Check out the rendering path docs to learn more about that. Next up is full page screenshots. For a while now, you've been able to take a screenshot of whatever was in the viewport, but now you can take a screenshot of the entire page, including everything above and below the fold. To take a screenshot, open up the command menu, type screenshot, and select Capture Full Size Screenshot. Wait a little bit, and DevTools eventually downloads the image. Next up is block request URLs. This lets you see how a page behaves when a URL or a pattern of URLs is blocked. This is useful for seeing how your page behaves when some scripts fail, or maybe a CDN goes down, and so on. Let's see how the DevTools homepage looks when its CSS is blocked. Go to the network panel, right-click on a request, and select Block Request URL. You can manage your blocked URLs in the Request Blocking tab that pops up at the bottom of your DevTools window. To block a pattern of URLs, click Add and enter a wildcard pattern. When I reload the page, yep, looks pretty broken, which you'd expect if you disabled all the CSS. Also, the network panel colors blocked requests in red. Last up is the Unified Command menu. In the past, there was one keyboard shortcut for opening files, and another one for jumping to a line, and so on. There's just a hassle to remember all the shortcuts, so now you can access them all from the Unified menu. When I open the Command menu, there's a greater than character in front of my cursor now. That's the symbol to run a command. If I replace that with a question mark, I can see all the other things I can do from the menu now, like running this handy snippet. That's what's new in DevTools in Chrome 59. Subscribe to the Chrome Developers YouTube channel to get our latest DevTools videos, and tweet us at Chrome DevTools to discuss any of these changes. I'll see you in six weeks when Chrome 60 gets released.