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WCAG 2.1 Contrast Ratio Checker
x402
WCAG 2.1 Contrast Ratio Checker is a paid API for AI agents from api.24klabs.ai, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-12).
Computes the WCAG 2.1 contrast ratio between a foreground and background color and reports AA/AAA pass/fail for normal and large text.
Price / call$0.002
Success—
StatusUnknown
How this service works
Compute the WCAG 2.1 contrast ratio between a foreground and background color and report AA/AAA pass/fail for normal and large text.
Output
Returns the numeric WCAG 2.1 contrast ratio (e.g. 4.5:1) between the two colors, along with pass/fail results for AA and AAA conformance levels for both normal text (requires 4.5:1 AA / 7:1 AAA) and large text (requires 3:1 AA / 4.5:1 AAA).
Example use cases
UI accessibility audit for brand colors
“I'm using our brand's coral red (#E8473F) for body text on a white (#FFFFFF) background — does that combination pass WCAG 2.1 AA and AAA for normal text?”
Dark mode color validation
“My dark mode uses light gray (#D1D5DB) text on a very dark background (#111827). Can you calculate the contrast ratio and tell me if it meets WCAG AA and AAA for both normal and large text?”
Button label readability check
“I want to put black (#000000) text on a yellow (#FFD600) button — what's the WCAG contrast ratio and does it pass AA accessibility standards for normal-sized text?”
Technical details
Endpoint
POSThttps://api.24klabs.ai/api/v1/wcag-contrast?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a programmatic, standards-authoritative WCAG 2.1 contrast ratio calculation with explicit AA/AAA pass/fail judgments for normal and large text — ideal for automated accessibility audits, design system validation, CI/CD checks, or any agent workflow that must enforce web accessibility compliance on color pairs.
Side effects
- Invalid or unparseable color value provided (e.g. malformed hex, unsupported format) returns a 4xx error
- Missing foreground or background color parameter returns a validation error
- Unsupported color format outside accepted range returns an error response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| bg | string | |
| fg | string |
Output
Schema · Response
{
"type": "json",
"example": {
"ratio": 4.48,
"AA_normal": true,
"AAA_normal": false
}
}Tags
x402
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