About Screen Test Tool

Screen Test Tool is a free, browser-based tool for displaying full-screen solid colors — white, black, red, green, blue, or any custom color you choose. It's built for checking monitors, laptops, and phones for dead pixels, stuck pixels, and backlight bleed, but it's just as useful as a plain full-screen background for calls, presentations, or ambient lighting.

Everything runs locally in your browser — there's no download, no account, and no data sent anywhere. It's built as a static site with plain HTML, CSS, and JavaScript, deliberately kept simple so it loads fast on any device.