For developers & designers

THE COLOR-
ACCESSIBILITY
PLATFORM

One published method for color-vision accessibility, everywhere you work — the same engine behind a checker, a fixer, a REST API, a one-line widget, a VS Code extension, a GitHub Action, and an MCP server.

Check whether colors stay distinguishable under color blindness, fix them if not, and correct pages for the people looking at them — all from a method that's published and open-access, so it can be verified rather than trusted.

The gate: the whole thing rests on one open-access paper — DOI 10.5281/zenodo.21310578 — Machado (2009) color-vision simulation + CIEDE2000 perceptual difference. Everything below runs that exact method. MIT-licensed, on GitHub.

THE ENGINE

npm · PyPI

Check, fix, contrast, and simulate — zero dependencies, byte-identical across JavaScript and Python.

npm install opticquiz-cvd      # JavaScript / TypeScript
pip install opticquiz-cvd      # Python (matplotlib, plotly, seaborn)
const cvd = require("opticquiz-cvd");
cvd.checkPalette(["#d7191c", "#1a9641"]).pass;   // false
cvd.fixPalette(["#d7191c", "#1a9641"]).colors;   // a safe version
cvd.checkContrast("#767676", "#ffffff").AA;      // true

npm · PyPI

THE API

REST · CORS

Anything that can hit a URL — a service, a CI job, an AI agent — can call the engine.

curl -X POST https://api.opticquiz.com/api/check \
  -H "Content-Type: application/json" \
  -d '{"colors":["#d7191c","#1a9641"]}'

/api/check · /api/fix · /api/contrast · /api/simulate · api.opticquiz.com/api

THE WIDGET

one line

A floating eye that lets your visitors re-color the page for their own color vision.

<script src="https://opticquiz.com/widget/eye.js" defer></script>

Docs & live demo · opticquiz-eye on npm

IN YOUR EDITOR

VS Code

Underlines color pairs that collapse for colorblind viewers as you write them, and fixes them with one click.

VS Code Marketplace — or search "colorblind" in the Extensions panel.

IN YOUR CI

GitHub Action

Fail a pull request when a stylesheet's colors collapse for colorblind viewers.

- uses: zengineco/opticquiz.com/packages/cvd-action@main
  with:
    path: ./src

FOR YOUR AI

MCP

Give Claude, Cursor, or any MCP client the tools to check and fix colors mid-conversation.

{ "mcpServers": { "opticquiz-cvd": {
  "command": "npx", "args": ["-y", "opticquiz-cvd-mcp"] } } }

opticquiz-cvd-mcp on npm

SHOW IT

live badge

A self-verifying badge that re-checks your palette every time it loads — a pass can't be faked.

colorblind-safe: pass

<img src="https://api.opticquiz.com/api/badge?colors=YOUR,HEX,COLORS">

OR JUST USE THE WEB TOOLS

Colorblind-safe palette checker — paste colors, get the conflicts and a fix.
Benchmark — is viridis / jet / Tableau / D3 / Material colorblind-safe?
WCAG contrast checker — the text-legibility axis.

Honest scope. These check and improve one axis — color distinguishability — and say so. They are screening and remediation aids, not a legal accessibility audit, and don't certify WCAG / ADA / EAA compliance, which cover far more than color. The method is published so its limits are documented, not hidden.