WCAG contrast audit API

Computes the WCAG 2.1 contrast ratio between a foreground and background and reports AA/AAA pass for normal & large text, the 3:1 non-text/UI threshold, both relative luminances, and an overall rating. Answers 'Does this text pass WCAG AA?', 'What is the contrast ratio?'

Price$0.04per request

MethodPOST

Route/v1/design/wcag-contrast

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

accessibilitywcagcontrasta11yaaaaacolorratioluminancedesign

API URLhttps://x402.hexl.dev/v1/design/wcag-contrast

Integration docs

Example request

{
  "foreground": "#777777",
  "background": "#ffffff"
}

Example response

{
  "foreground": "#777777",
  "background": "#ffffff",
  "ratio": 4.48,
  "ratioString": "4.48:1",
  "relativeLuminance": {
    "foreground": 0.1845,
    "background": 1
  },
  "passes": {
    "aaNormal": false,
    "aaLarge": true,
    "aaaNormal": false,
    "aaaLarge": false,
    "uiComponents": true
  },
  "rating": "AA Large",
  "interpretation": "Contrast 4.48:1 meets AA Large."
}

Input schema

{
  "type": "object",
  "required": [
    "foreground",
    "background"
  ],
  "properties": {
    "foreground": {
      "type": "string",
      "examples": [
        "#777777"
      ]
    },
    "background": {
      "type": "string",
      "examples": [
        "#ffffff"
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}