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Colour-Blindness Simulator
See a design as different types of colour vision do.
100% FreeRuns instantlyNo watermark
- 1Choose toolOpen the Vootkit workspace.
- 2Add inputProvide the content or settings.
- 3ProcessLet the browser do the work.
Private by designProcessed on your device where possible.
Works on any deviceDesktop, tablet and mobile browsers.
No installationOpen the page and start working.
Always free coreUse the free plan for everyday tasks.
How to use Colour-Blindness Simulator
Provide the content or settings.
02Let the browser do the work.
03Copy, download or continue.
04Your files stay private
Your work is processed locally in your browser where possible and is never added to a Vootkit upload library.
Learn more about privacyAround one in twelve men has some form of colour vision deficiency, and the commonest design failure is not a bad colour — it is using colour alone to carry meaning that some users cannot see.
What Colour-Blindness Simulator does
Simulates the three main types: protanopia (red-weak), deuteranopia (green-weak, the most common) and tritanopia (blue-weak, rare).
The point is not to design for the simulation but to find places where colour is the only signal — a red error state, a green success tick, a chart distinguished purely by hue.
The three types
| Deuteranopia | Green-weak — the most common form |
|---|---|
| Protanopia | Red-weak |
| Tritanopia | Blue-weak — rare |
| Affects roughly | 1 in 12 men, 1 in 200 women |
| Classic failure | Red/green as the only distinction |
| <strong>The fix</strong> | <strong>Never use colour alone — add text, icon or pattern</strong> |
| Complements | Contrast checking — different problem |
| Runs | On your device |
Detailed steps
- Load the design or chart.
- Compare the simulations, especially deuteranopia.
- Anywhere meaning collapses, add a second signal — a label, an icon, a pattern.
Worth knowing
The fix is almost never a different colour — it is a second signal. Add an icon to the error state, a label to the chart line, a pattern to the bar. That works for every type of colour vision deficiency at once, survives greyscale printing, and helps in bright sunlight too. Choosing a "colour-blind-safe" palette solves one case; a second signal solves all of them.
Frequently Asked Questions
Which type should I design for?
Check all three, but deuteranopia is the most common by a wide margin. If a design survives that and carries a non-colour signal everywhere meaning depends on it, the others are largely covered.
Is red-green really the main problem?
Yes — it accounts for the overwhelming majority of cases, which is unfortunate given how universally red means bad and green means good in interfaces. That convention is exactly the one that fails.
Does high contrast solve it?
No. They are separate problems. A red and a green of identical luminance pass contrast checks and are indistinguishable to a deuteranope. Both checks are needed.
How do I fix a chart?
Label the lines directly rather than relying on a colour key, or vary line style and marker shape as well as colour. Direct labelling is better for everyone, not only colour-blind readers.
Is Colour-Blindness Simulator free?
Yes. The Vootkit free plan includes 5 tool runs a day. Upgrade to Vootkit Pro for unlimited daily use, an ad-free workspace and saved workflows.
Are my files uploaded?
No. Colour-Blindness Simulator runs entirely in your browser — your file is processed on your own device and never sent to a server. There is nothing for us to store or delete.
Do I need to install anything?
No. Colour-Blindness Simulator works in any modern browser on desktop, tablet or phone. Open the page and start.
How often can I use it? Is there a daily limit?
On the free plan you get 5 tool runs a day. When you reach the limit you'll see a prompt to upgrade, and it resets the next day. Vootkit Pro removes the cap entirely for unlimited daily use.
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This tool processes everything locally in your browser. You can disconnect from the internet after the page loads and it will still work.