Local · Private · Free

Color Blindness Simulator

Preview any image — or a color pair — through all eight color-vision deficiency types, with a severity slider and WCAG contrast per mode. Nothing is uploaded.

👁
Drop an image here
or click to browse — JPG, PNG, WebP
🔒 Files never leave your browser — all simulation happens locally on your device

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

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).

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. See how an image looks with protanopia, deuteranopia, tritanopia & more. Because everything happens locally on your device, your files and data are never uploaded to a server, there is no sign-up or installation required, and it keeps working offline. It is handy for color blindness, accessibility, protanopia, deuteranopia. Like every HeroTool by Digital Heroes, Color Blindness Simulator is 100% free with no limits.

How to use Color Blindness Simulator

  1. Open Color Blindness Simulator — it runs entirely in your browser, with no signup.
  2. Drag and drop your file (or click to browse) — it never leaves your device.
  3. Adjust the options to match exactly what you need.
  4. Copy or download your result — it is free, and 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. HeroTools 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?

See how an image looks with protanopia, deuteranopia, tritanopia & more.