Cleaning a monitor
A bright, even screen makes dust, smudges and fingerprints obvious. Check first, power the display off, then wipe with a dry microfibre cloth.
Colour blindness test
Run a full colour blindness test straight from your browser. Everything happens on your own device — no upload, no account, nothing installed. It works the same on a phone, a tablet, a laptop screen or a 4K desktop monitor, and it takes under a minute.
F Tap anywhere to go fullscreen
Click the screen or press F. Press Esc to exit. · 100% free. No sign-up. Works offline.
These plates are drawn in the style of the Ishihara test: a circle of coloured dots in which a numeral is picked out purely by hue, with brightness and dot size deliberately randomised so the figure cannot be found by contrast alone. Someone with typical colour vision reads the number easily; someone with a red-green deficiency may read a different number or none at all.
This is a screening aid, not a diagnosis. Screen rendering, ambient light and your display's colour accuracy all affect the result, and a genuine assessment uses printed plates under controlled lighting followed by an optometrist's examination.
It has a second use that has nothing to do with your eyes. If you design interfaces, these plates are a quick reminder of how much information disappears when hue is the only thing distinguishing two states.
What this checks
- Whether the numeral is legible on each plate at a normal viewing distance
- Consistency between plates — different plates target different deficiency types
- How your own display renders closely related hues, which affects the result
- For designers: how much meaning is lost when colour alone carries it
How to use it
Open the screen
Click or tap the preview panel. Your browser switches to true fullscreen and hides every menu bar and toolbar.
Adjust it
Use the brightness slider and the colour temperature control to get exactly the light you need. Your settings are remembered on this device.
Use it
Clean, test, light or focus. Move the mouse or tap once to bring the controls back at any time.
Exit
Press Esc, or tap the close button in the corner, to return to this page.
What people use it for
Finding dead pixels
A dead pixel stays black on white; a stuck pixel glows red, green or blue on black. Cycling solid colours is still the fastest way to find both.
Video call lighting
A white or warm-white screen beside your face fills in shadows far better than a ceiling light, and costs nothing.
Photography and video
A tablet running a solid colour makes a usable fill light, catch light or small backdrop for product shots.
Tracing and drawing
A tablet on maximum brightness under thin paper works as an improvised light table for tracing and flip-book animation.
Focus and presenting
A blank screen hides your desktop during a presentation and removes visual clutter while you concentrate.
Frequently asked questions
Is the colour blindness test really free?
Yes. Every tool on this site is free, with no account, no trial and no paid tier. You do not need to give us an email address.
Does it work on a phone or tablet?
Yes. The whole site is built mobile-first and works in Safari on iPhone and iPad, Chrome on Android, and every modern desktop browser. On iOS, fullscreen uses a full-viewport mode because Safari restricts the fullscreen API.
Does it work offline?
Yes. After your first visit the page is cached on your device, so you can open it again with no internet connection at all.
Will this damage my screen?
No. Displaying a solid colour is exactly what your screen does all day. The one caution is OLED: leaving a static bright image on an OLED panel for hours can cause temporary image retention, which is why we include an optional burn-in protection mode.
Do you collect my data?
We do not ask for a name, an email or an account, and no image ever leaves your device — every tool renders locally in your browser.
Is this a real colour blindness test?
It is a screening aid built in the style of the Ishihara plates, not a clinical test. Screen calibration and room lighting both change the result. If you cannot read the plates, see an optometrist for a proper assessment rather than concluding anything from a web page.
I could read some plates but not others.
That is common and is how the real test works — individual plates target different types and severities of deficiency. Partial results are worth following up properly rather than self-diagnosing.
How should designers use this?
As a reminder that hue alone is not an accessible way to encode meaning. Anything communicated by colour — status, validity, categories in a chart — needs a second cue such as a label, an icon, a pattern or a difference in brightness.