About White Screen Tool

White Screen Tool is a set of full screen colour screens and monitor tests that run entirely in your browser. There are ten colour screens, from pure white through to mid grey, and nine tests covering dead pixels, stuck pixels, backlight bleed, uniformity, colour accuracy, banding, refresh rate, resolution and ghosting. All of it is free, none of it needs an account, and nothing about your display is sent anywhere.

Why it exists

There are plenty of pages that paint a browser window white. Nearly all of them stop there, and stopping there answers only the simplest version of the question. Someone cleaning a monitor needs to switch between white and black. Someone hunting a dead pixel needs every primary in sequence, because a pixel that is dead on white can look perfect on red. Someone using a laptop as a fill light needs the brightness down and a timer so the screen closes itself. Those are three different jobs and they need more than a white rectangle.

So this site has the rectangle, and then it has the controls: a brightness slider that scales the colour rather than relying on your monitor, an automatic colour cycle for pixel hunting, a countdown timer, and the hex code printed under every chip so you can verify that white really is #FFFFFF.

How it works, and what it does not do

Every test here is a small amount of JavaScript painting colours and measuring frames in your browser. The refresh rate readout is your own browser timing its own frames. The resolution readout is your own browser reporting its own display. Neither figure leaves your machine, because neither one ever needs to.

The site asks for no camera, no microphone, no location and no account. It sets no advertising cookies today. If display advertising is ever added, it will be disclosed on the privacy page before it appears, not afterwards.

Honest limits

A browser cannot measure everything, and it is worth being clear about where the line is. The ghosting test shows you smearing and overshoot clearly enough to tune an overdrive setting, but it cannot give you a response time in milliseconds, because that needs a photodiode and an oscilloscope rather than a web page. The refresh rate test reports the rate your browser is being allowed to draw at, which is not always the rate the panel is scanning at. And no web page can calibrate a display, only show you whether one needs calibrating.

The guides

Finding a fault is half the problem. The guides cover what to do next: telling a stuck pixel from pressure damage, cleaning a coated panel without stripping the coating, working out whether a line down a screen is the panel or the cable, and deciding when a fault is worth a repair and when it is worth living with. They are written to be useful before you spend money, which means several of them conclude that the honest answer is to do nothing.

Contact

Corrections, bug reports and suggestions are welcome, particularly if a test behaves oddly on a device or browser combination worth knowing about. Email hello@whitescreentool.com, and include the browser and the device if you are reporting a fault.