Colour utilities
Colour utilities: ?op=convert (default) turns any hex/rgb()/hsl()/CSS-name into hex, rgb, hsl, hsv, alpha, relative luminance and exact CSS name; ?op=contrast with ?fg=&bg= returns the WCAG 2.x contrast ratio and AA/AAA pass/fail for normal & large text plus UI components (accessibility / EAA); ?op=palette derives complementary, analogous, triadic, tints and shades. Send hex without '#'.
Not tested: has real-world effectsour last check, 2026-09-24
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Endpoint
GET https://402utils.com/v1/color
| Category | Everything else |
|---|---|
| Provider host | 402utils.com |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 6 from 5 payers (the provider's figure, not ours) |
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We never call tools that send, buy, move money or file anything, not even without paying.
Example input (from the provider)
{
"method": "GET",
"queryParams": {
"bg": "ffffff",
"fg": "000000",
"op": "contrast"
},
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"method": {
"enum": [
"GET"
],
"type": "string"
},
"queryParams": {
"description": "Query string only.",
"properties": {
"bg": {
"description": "Background colour (op=contrast). Falls back to `color` for fg.",
"type": "string"
},
"color": {
"description": "The colour (convert/palette): hex without '#', rgb(), hsl() or a CSS name.",
"type": "string"
},
"fg": {
"description": "Foreground colour (op=contrast).",
"type": "string"
},
"op": {
"default": "convert",
"enum": [
"convert",
"contrast",
"palette"
],
"type": "string"
}
},
"type": "object"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"description": "Shape depends on `op`.",
"properties": {
"AA": {
"description": "AA pass/fail for normalText, largeText, uiComponents.",
"type": "object"
},
"AAA": {
"description": "AAA pass/fail for normalText, largeText.",
"type": "object"
},
"analogous": {
"items": {
"type": "string"
},
"type": "array"
},
"complementary": {
"description": "(op=palette).",
"type": "string"
},
"hex": {
"type": "string"
},
"hsl": {
"type": "object"
},
"hsv": {
"type": "object"
},
"luminance": {
"description": "WCAG relative luminance 0-1 (op=convert).",
"type": "number"
},
"name": {
"description": "Exact CSS colour name, if any.",
"type": [
"string",
"null"
]
},
"op": {
"type": "string"
},
"ratio": {
"description": "WCAG contrast ratio 1-21 (op=contrast).",
"type": "number"
},
"rgb": {
"type": "object"
},
"shades": {
"items": {
"type": "string"
},
"type": "array"
},
"tints": {
"items": {
"type": "string"
},
"type": "array"
},
"triadic": {
"items": {
"type": "string"
},
"type": "array"
}
},
"required": [
"op"
],
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}