Local · Private · Free

Color Blindness Simulator

Preview any image, or a color pair, through all eight color-vision deficiency types. Adjust severity, check WCAG contrast ratios per mode, and download the result. Nothing is uploaded, everything runs locally in your browser.

Drop an image here
or click to browse, JPG, PNG, WebP

Files never leave your browser, all simulation happens locally on your device

Vision type

Severity100%

100% = full deficiency · lower values blend toward normal vision (useful for the “-anomaly” types)

View

Compare slots (original + 3)

Format

Export size

Burn mode labels into exports

Color-pair tester

Check how a text / background pair holds up under every vision type, with the WCAG contrast ratio recalculated per mode (uses the severity slider above).

Text color

Background color

AA = ratio ≥ 4.5 (normal text) · AA-L = ratio ≥ 3 (large text ≥ 24px / 18.66px bold)

How the simulation works

Each vision type is approximated with an established 3×3 RGB color matrix (the widely used Colorjack / machado-style daltonization matrices), applied pixel-by-pixel on a canvas. Around 8% of men and 0.5% of women have some form of color-vision deficiency, deuteranomaly (green-weak) is by far the most common. Everything runs locally; your image never touches a server. Free forever.

About Color Blindness Simulator

Color Blindness Simulator is a free, private image tool that runs entirely in your web browser. Drop any image to see it through 8 color-vision deficiency types, including protanopia, deuteranopia, and tritanopia. A severity slider lets you blend from full deficiency down to normal vision. The built-in color-pair tester recalculates WCAG contrast ratios for every vision mode. Because everything happens locally on your device, your files are never uploaded. No sign-up or installation required. Like every tool by Digital Heroes, it is 100% free with no limits.

What you can do

Simulate 8 vision types including protanopia, deuteranopia, tritanopia, and achromatopsia on any image.

Adjust severity from 0% to 100% to show partial or full color-vision deficiency.

Compare 4 views side by side in a 2x2 grid with your own choice of vision modes.

Test any color pair and see the WCAG contrast ratio recalculated for every deficiency type at once.

Download the simulated image or a labeled 2x2 comparison grid as PNG, JPG, or WebP.

Export a CSV report of contrast ratios across all 8 vision types for documentation or accessibility audits.

How to use Color Blindness Simulator

Open Color Blindness Simulator. It runs entirely in your browser with no signup.

Drop an image (or click to browse). The file never leaves your device.

Pick a vision type and adjust the severity slider to preview the deficiency.

Switch to 2x2 compare view to see multiple modes at once, or use the color-pair tester to check WCAG contrast.

Download your result as PNG, JPG, or WebP. Your data stays on your device.

Frequently asked questions

Is Color Blindness Simulator free?

Yes, Color Blindness Simulator is completely free for everyone. No sign-up, no account and no usage limits.

Is it private? Are my files uploaded anywhere?

No. Color Blindness Simulator runs entirely in your browser on your own device, so your data never leaves your computer and nothing is uploaded to a server.

Does it work offline?

Yes. This tool is a Progressive Web App, once the page has loaded it keeps working offline, and you can install it as an app from your browser.

Do I need to install anything or create an account?

No. Just open the page and start using it. Installing it as an app is optional and only adds offline convenience.

What does Color Blindness Simulator do?

It applies color-vision deficiency matrices to any image so you can see it through 8 different vision types: protanopia, deuteranopia, tritanopia, and more. It also checks WCAG contrast ratios for any color pair across every vision mode, and lets you download the results.