DeadPixel is a free, single-purpose screen test: it floods your display with solid colors so dead and stuck pixels can’t hide, then gives you a safe way to exercise stuck ones. It exists for the moment every screen owner eventually hits — a new monitor on the desk, a suspicious dot in the corner of your eye, a warranty claim you need evidence for.

What the tester does

• Fullscreen color cycling — black, white, red, green and blue, plus a custom hue from the slider. Each screen isolates a different fault: black reveals glowing stuck sub-pixels, white reveals dead pixels, the primaries isolate single dead channels.
• Auto-cycle mode — hands-free color rotation on an interval you set, so you can scan the panel instead of pressing keys.
• A stuck-pixel exerciser — a small, draggable box that flashes rapid color sequences over a stuck dot. It’s deliberately gated behind a photosensitivity consent prompt, capped in size and speed, and session-timed.
• A guide overlay — press H inside the test for a plain-language key to what each screen can reveal.
• Fullscreen with a fallback — the Fullscreen API where the platform supports it, a full-page overlay where it doesn’t (iPhone Safari, embedded browsers). Tap, keyboard and mouse controls all work either way.

How it works under the hood

There is no app, no install and no server-side component. The tester is a single JavaScript file that paints the browser viewport — which is also why it’s trustworthy as a diagnostic: it runs below your OS, your apps and your GPU’s whims. If a dot survives all five screens here, it’s in the panel, not the software.

Who maintains it

DeadPixel is built and maintained by a small independent team that ships focused utility sites. The guides on this site — dead vs. stuck, warranty policies, fix methods, the new-monitor routine — are written to be the thing we wished existed the first time we found a dead sub-pixel past a return deadline.

Found a screen the tester misrenders, a policy that changed, or a fix that worked for you? Contact us — hardware reports go to the front of the queue.