Colour Converter API

Design

Convert between colour formats (HEX, RGB, HSL, CMYK) with a colour picker and text contrast detection.

Authentication

All API requests require a valid API key passed in the Authorization header as a Bearer token.

Rate Limit

100 requests per minute

Endpoints

1 endpoint available

Overview

The Colour Converter API converts colours between multiple formats. Input any colour format and receive all formats in the response - HEX, RGB, RGBA, HSL, HSLA, CMYK, Display P3, and LCH.

Supported Input Formats

HEX - #FF5733, #f53, FF5733 (with or without #)
RGB - rgb(255, 87, 51)
RGBA - rgba(255, 87, 51, 0.8)
HSL - hsl(9, 100%, 60%)
HSLA - hsla(9, 100%, 60%, 0.8)
Named Colors - red, blue, tomato, coral, etc.

Output Formats

Every response includes all of these formats:

hex - HEX format (#FF5733)
rgb - RGB format
rgba - RGBA format with alpha
hsl - HSL format
hsla - HSLA format with alpha
cmyk - CMYK format for print
displayP3 - Display P3 wide gamut format
lch - LCH perceptually uniform format
name - Colour name if recognized
bestTextColor - Recommended text color (black or white) for contrast

Use Cases

CSS colour format conversion
Design system colour management
Accessibility contrast checking
Print-ready CMYK conversion

Endpoints

POST

/v1/tools/colour-converter

Convert a colour to all supported formats

Request Body

Content-Type: application/json

Parameter	Type	Required	Description
colour	string	Required	The colour to convert (any supported format)

Response Example

{
  "success": true,
  "result": {
    "hex": "#FF5733",
    "rgb": "rgb(255, 87, 51)",
    "rgba": "rgba(255, 87, 51, 1)",
    "hsl": "hsl(11, 100%, 60%)",
    "hsla": "hsla(11, 100%, 60%, 1)",
    "cmyk": "cmyk(0, 66, 80, 0)",
    "displayP3": "color(display-p3 0.92 0.39 0.25)",
    "lch": "lch(57.58 75.55 40.85)",
    "name": "Orange Red",
    "bestTextColor": "white"
  }
}

Error Codes

400

Invalid request body or missing colour

401

Missing or invalid API key

422

Invalid colour format

429

Rate limit exceeded

500

Internal server error

Code Examples

# Convert HEX to all formats
curl -X POST https://api.opentools.ca/v1/tools/colour-converter \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"colour": "#FF5733"}'

# Convert named colour
curl -X POST https://api.opentools.ca/v1/tools/colour-converter \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"colour": "coral"}'

Ready to get started?

Create an API key to start using the Colour Converter API.