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WCAG Contrast Ratio Checker
x402
WCAG Contrast Ratio Checker is a paid API for AI agents from api.webbersites.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-10).
Calculates the WCAG contrast ratio between a foreground and background color, returning the exact ratio and AA/AAA pass/fail verdicts for normal text, large text, and UI components.
Price / call$0.001
Success—
StatusUnknown
How this service works
WCAG contrast ratio between two colors — the check the URL-based a11y endpoint can't do. Give a foreground and background color (hex or rgb()); returns the exact ratio and AA/AAA pass/fail for normal text, large text, and UI components, with a plain-English verdict. ?fg=&bg=
Output
Returns the exact numeric contrast ratio (e.g. 7.43:1), plus pass/fail status for WCAG AA and AAA levels across three contexts — normal text, large text, and UI components — along with a plain-English summary verdict.
Example use cases
Example prompt
“What's the WCAG contrast ratio between foreground color #1a1a2e and background color #f0f4f8 — does it pass AA and AAA for normal text, large text, and UI components?”
Technical details
Endpoint
GEThttps://api.webbersites.com/api/a11y/contrast?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need the precise WCAG contrast ratio computation between two specific colors, including separate AA/AAA verdicts for normal text, large text, and UI components. Prefer this over general URL-based accessibility checkers that cannot accept arbitrary color pairs as input.
Side effects
- Missing fg or bg parameter returns a 400 error
- Invalid color format (not hex or rgb()) returns a parsing error
- Malformed hex codes (e.g. wrong length) may return an error or unexpected result
- Network timeout if the service is temporarily unavailable
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"passes": {
"large_text": {
"AA": true,
"AAA": true
},
"normal_text": {
"AA": true,
"AAA": false
}
},
"summary": "Good — passes AA for normal text and AAA for large text.",
"background": "#ffffff",
"foreground": "#767676",
"ratio_string": "4.54:1",
"contrast_ratio": 4.54
}
}Tags
x402
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