Flicker Button
Dead pixel, keyboard & mouse testers
01Screen test
Fill the whole screen with one colour at a time and look for any dot that does not match. Works on any screen with a browser.
Solid colour test
Black: Stuck and hot pixels light up as coloured or white dots.
→ or Space next · ← back · H hide the label · Esc exit. On a touch screen, tap to change colour.
Flashing tool
Photosensitivity warning. This tool flashes a small square rapidly between red, green, blue, white and black. Flashing light can trigger seizures in people with photosensitive epilepsy, and headaches or migraines in others. Do not use it if that could apply to you or to anyone who can see the screen.
While it runs, look away or cover the square with a sheet of paper. Press Esc or the red Stop button to end it at once. It also pauses by itself when the timer runs out or you switch to another tab.
Your device asks for reduced motion, so the exerciser starts at its slowest speed.
It opens on a black screen with an outlined square that is not flashing yet. Drag the square over the stuck pixel, or move it with the arrow keys, then press Start flashing.
Wipe the screen with a dry microfibre cloth first: a speck of dust looks exactly like a dead pixel until it moves. Set the brightness to where you normally use it, start the full-screen test and step through every colour. Scan the screen in sections from your usual seat, then look closer at anything odd. Black shows pixels that are lit when they should be off; white and grey show pixels that stay dark; red, green and blue test each subpixel on its own.
A dot that changes or disappears when you tilt your head is more likely dust or a mark on the surface than a faulty pixel.
The exerciser only makes sense for stuck pixels. Move the square over the dot, run it for 10 to 20 minutes, then check again on black and on the dot's colour. Some stuck pixels recover, many do not, and a dead pixel will not. If a new screen has a fault, note where it is and contact the seller while you can still return it: makers' pixel policies differ in how many faulty pixels they accept.
Screens, keyboards, mice and controllers.
Black and grey levels to show backlight bleed, IPS glow, clouding and dark corners.
Every key on an ANSI, ISO or Mac board, with key codes, rollover and chatter detection.
All five buttons, accidental double-clicks, wheel steps and a polling rate estimate.
Your screen's real frame rate, a frame-time graph and moving-block and frame-skip checks.
Buttons, triggers and sticks with a dead-zone view, stick drift check and rumble test.
Two free services for the rest of your setup.
Hardware giveaways, price-drop alerts and the forum where someone fixed your exact keyboard all want an email address first. CleanTempMail gives you a free temporary inbox straight away, with a random or custom address on hundreds of domains, and deletes the messages after 3 days.
Keep your real address for warranty registrations and receipts.
Open a temporary inboxSetting up a new machine? WebTraceCheck's free tools check your connection's IPv4, IPv6, DNS and WebRTC details and whether your browser supports WebGPU. Its disposable cloud browser runs Chrome, Firefox, Edge, Brave or Chromium on an isolated Linux desktop that is deleted after each session.
Nothing to install, with free time every day.
Try WebTraceCheckUsually not. A pixel that stays black on every colour has stopped switching, and software cannot change that. Stuck pixels are different: some recover after a session with the exerciser, or on their own after a few days of normal use.
So the browser's bars and your taskbar do not hide pixels along the edges. Where a browser cannot make a page full screen, as on iPhone, the test fills the browser window instead: check the strip under the address bar separately, for example by turning the phone round.
We would not. Some guides suggest pressing on the spot through a cloth, but pressing on a panel can damage it and leave a bigger mark than the one you started with. If the exerciser does not help and the screen is new, use the seller's returns or the warranty instead.
Black and white catch most faults, and they take a few seconds. Red, green and blue matter when you see a coloured dot and want to know which subpixel is at fault, and grey is the easiest way to spot dim patches and smudges.