Accessible Palette Checker API

Adjust the lightness of palette colours as little as possible (in OKLCH, hue kept) until chosen foreground/background pairs meet a WCAG contrast target.

POST /api/v1/tools/palette-contrast-fixerMCP palette_contrast_fixerDesign & Colour

Check every text and background pair in your palette against WCAG AA and AAA, then fix failing pairs by nudging OKLCH lightness as little as possible.

Input

Send these as a JSON object. Unknown fields are rejected.

colors: 2 to 10 colours, one per line or comma-separated (hex, rgb(), hsl() or names). They are numbered from 1 in this order. (string, up to 2000 characters, required)
pairs: Pairs to fix as 1-based colour numbers, comma-separated, e.g. "1-2, 1-3" (text colour 1 on background 2 and 3). (string, up to 500 characters, required)
adjustable: Colour numbers allowed to change, comma-separated, e.g. "1". Default: every colour. (string, up to 100 characters)
target: aa: AA, normal text (4.5:1); aa-large: AA, large text and UI (3:1); aaa: AAA, normal text (7:1). (string, one of aa, aa-large, aaa, default "aa")

Try it in the browser JSON Schema Get an API key

curl https://pithlab.com/api/v1/tools/palette-contrast-fixer \n  -H "Authorization: Bearer $PITHLAB_KEY" \n  -H "Content-Type: application/json" \n  -d '{"colors":"#777777, #ffffff, #f1f5f9","pairs":"1-2, 1-3","adjustable":"1","target":"aa"}'

Example response

{
  "ok": true,
  "result": {
    "colors": [
      "#707070",
      "#ffffff",
      "#f1f5f9"
    ],
    "changes": [
      {
        "color": 1,
        "before": "#777777",
        "after": "#707070",
        "deltaL": -0.0241
      }
    ],
    "pairs": [
      {
        "foreground": 1,
        "background": 2,
        "before": "4.47:1",
        "after": "4.95:1",
        "level": "AA",
        "passes": true
      },
      {
        "foreground": 1,
        "background": 3,
        "before": "4.08:1",
        "after": "4.52:1",
        "level": "AA",
        "passes": true
      }
    ],
    "allPass": true
  }
}