https://bleckscreen.com/

Bleckscreen.com is a simple, browser-based tool designed to help you test and inspect your display by showing a full black or white screen directly in your browser — no downloads or software installs required. When you switch to the all-black screen mode, it covers your entire display with a pure dark background, making it much easier to spot common issues like dead or stuck pixels, backlight bleeding, uneven brightness, clouding, or minor color inconsistencies that would otherwise be hard to notice during normal use. Because a blank black screen removes all visual distractions, even tiny imperfections stand out clearly, giving you a quick and reliable way to evaluate the health and uniformity of your monitor, laptop, TV, or mobile screen.