Color blindness simulator
Drop in a screenshot, chart or photo to see it side by side as people with color vision deficiencies see it. Switch between eight types instantly and download the simulated image. Everything runs on your device — nothing is uploaded.
Drop an image or screenshot
Simulates 8 types of color blindness, privately.
How to use the color blindness simulator
- Drop or choose an image (screenshots of your UI work best).
- Pick a type of color blindness.
- Compare the original and the simulation side by side.
- Download the simulated image to share with your team.
Why test for color blindness?
Around 1 in 12 men and 1 in 200 women have some form of color vision deficiency. Charts, status colors and links that rely on red versus green are the most common problems. Checking a simulation helps you add labels, patterns or contrast so information never depends on color alone.
How the simulation works
Swatchly uses the Machado, Oliveira and Fernandes (2009) model for protan, deutan and tritan deficiencies, applied in linear RGB, plus luminance-based models for achromatopsia and achromatomaly.
Frequently asked questions
What is the most common type of color blindness?
Deuteranomaly — reduced sensitivity to green — affecting about 5% of men.
Are my images uploaded?
No. The simulation runs entirely in your browser with WebAssembly.