Best Color Blind Simulators & Accessibility Testing Tools (2026)
The tools we actually use, how accurate they really are, and which one to reach for in each situation.
Jul 18, 2026Read more →
Free · Private · No sign-up
Color Blindness Simulator
Test color blindness and simulate color-blind vision to build accessible designs. Upload images, use your live webcam, or check color palettes — fast, easy, and privacy-friendly.
9
vision types simulated
100%
in your browser
Free
no sign-up, no watermark
Research
based color models
A color blindness simulator for real design work
Roughly 300 million people — about 1 in 12 men and 1 in 200 women — see color differently than you do. This color blindness simulator lets you view any image, screen, or live website the way they would, so you can fix the places a design leans on color alone. Pick a tool below and test something in the next minute.
One simulator, five ways to test
Images, palettes, your webcam, a live URL, or your own color vision.
Image Simulator
Upload a photo, screenshot, or graphic — or paste a URL — and compare it side by side with any of the nine color-blindness types.
Palette Checker
Paste your brand or UI colors and see which pairs stop being distinguishable, with a contrast readout for each.
Live Webcam
Turn on your camera and see a room, a product, or a printout through a color-blind filter in real time as you move.
Website Checker
Enter a URL and get a full-page screenshot of your live site the way color-blind visitors actually see it.
Color Blind Test
Take a 30-plate Ishihara-style test to screen your own color vision in a couple of minutes.
Works everywhere
Runs in any modern browser on desktop, tablet, and phone. Nothing to install, and no account to create.
How the color blindness simulator works
Color blindness comes from the eye's three cone types responding differently — or one type missing entirely. To recreate that, the simulator reads your image pixel by pixel, converts each color from the gamma-encoded sRGB your screen uses into linear light, and runs it through a matrix that models how a specific deficiency shifts the cone signal. The colors are then converted back to sRGB so they display correctly. The models come from published research (Machado et al. and the Brettel–Viénot approach), not a quick channel swap, which is why the results line up with how color blindness is described clinically.
It covers the full range of color vision deficiency — the three dichromacies, the three anomalous trichromacies, and the monochromacies — nine types in all. For images and webcam, every step runs in JavaScript on your device, so nothing you test is uploaded.
A note on accuracy
A simulator is an approximation, not a literal window into someone's vision. It's most reliable for the dichromacies, where a cone type is missing; the milder anomalous types vary between individuals. Your monitor's calibration affects the result too. It's a design and learning tool — it can't diagnose color blindness. For that, take the color blindness test or see an eye-care professional.
Why it matters
When color is the only thing separating two states — a green “paid” badge from a red “overdue” one, a required field marked only in red, a chart that relies on its legend — a large share of your users can miss it. Testing early is far cheaper than reworking a shipped design, and it's exactly what accessibility standards ask for.
WCAG Success Criterion 1.4.1 says color can't be the only way you convey information. A color blindness simulator is the fastest way to check that, and it pairs naturally with a contrast check for the rest.
Who uses it
Designers
Preview mockups and graphics before handoff, and catch color-only choices while they're still cheap to change.
Developers
Check components, charts, and status colors against WCAG before you ship a build.
Educators
Show a class or a team, in one glance, why “just use red” leaves people out.
Accessibility testers
Document real issues with side-by-side screenshots for your audit reports.
Why you can trust the results
We build these tools for our own accessibility work, so they're made to be accurate, private, and honest about what they can and can't do.
Grounded in published research
Simulations use cone-response models from the color-vision literature (Machado and Brettel–Viénot), not a rough channel swap.
Private by default
Image and webcam processing runs entirely on your device. Your files are never uploaded, stored, or shared.
Honest about limits
A simulator approximates color-blind vision — it's most reliable for dichromacy and can't diagnose anyone. We say so plainly.
Free, no strings
Every tool is free for personal and commercial use, with no account, no paywall, and no watermark on downloads.
From the blog
How to Design for Color Blind Users: A Practical UI Guide (2026)
Core principles plus concrete UI patterns for errors, charts, links, and status — with WCAG contrast rules.
Jul 18, 2026Read more →
How to Choose Accessible Color Palettes for Your UI (2026)
Vary lightness, not just hue, avoid the risky color pairs, and use color-blind-safe palettes that hold up.
Jul 18, 2026Read more →
Frequently asked questions
What is a color blindness simulator?
A color blindness simulator shows how an image, website, or design looks to someone with color vision deficiency. You upload a picture, point your webcam, or enter a URL, and it re-renders the colors the way a color-blind person would see them — so you can catch problems your own eyes miss.
How accurate is the color blindness simulation?
It's a close approximation, not a perfect copy of anyone's vision. The results come from published color-science models and are most reliable for the dichromacies (protanopia, deuteranopia, tritanopia). The milder “anomalous” types vary from person to person, so treat those as a good estimate rather than an exact match.
Which types of color blindness can I simulate?
All nine: protanopia, deuteranopia, and tritanopia (dichromacy); protanomaly, deuteranomaly, and tritanomaly (anomalous trichromacy); and achromatopsia, blue-cone monochromacy, and rod monochromacy.
Is the color blindness simulator free?
Yes. Every tool here is free for personal, educational, and commercial use, with no sign-up and no watermark on your downloads.
Are my images uploaded anywhere?
No. Image and webcam processing happens in your browser, on your device — nothing is sent to a server or stored. The one exception is the Website Checker, which loads the public URL you enter on our server to take the screenshot.
Can it tell me whether I'm color blind?
Not on its own — the simulator shows how others see your work. For a quick self-check, take the color blindness test; for an actual diagnosis, see an optometrist or ophthalmologist.
Test a design in the next minute
Free, private, and no sign-up. Start with an image and go from there.