Color Contrast & Conversion API

What it does

Color Contrast Checker compares a foreground and background color and returns the contrast ratio plus WCAG pass flags. Send two color values in the request body as foreground and background, and use the response to verify accessibility before you ship a UI.

The /design/contrast endpoint returns ratio from 1 to 21, along with aa, aaLarge, and aaa booleans. If the input is invalid, you get an error message instead of a contrast result. That makes it straightforward to plug into design systems, component libraries, or automated checks for button labels, charts, and other text-on-color combinations.

Color Contrast Checker also includes /design/color-convert for translating colors between hex, rgb, and hsl. Provide a hex string or RGB channel values in the request body, and get back normalized hex, rgb, and hsl values. Use it when you need to accept one format from a design tool and store or display another in your app.

▣ ENDPOINT 01 / 02

POST

WCAG Color Contrast Checker

https://api.eu.apyhub.com/freedailypro/color-contrast-conversion-api/design/contrast

QUICKSTART

GUIDE

Quickstart

Compare a foreground and background color for contrast by sending both hex values in the request body.

curl -X POST "https://api.eu.apyhub.com/freedailypro/color-contrast-conversion-api/design/contrast" \
  -H "apy-token: $APY_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"foreground":"#000000","background":"#ffffff"}'

What you'll get back

The live response to the request above:

{
  "tool": "Contrast checker client and server side from freedailypro",
  "ratio": 21,
  "aa": true,
  "aaa": true,
  "aaLarge": true
}

TRY ITLIVE · 10 ATOMS

API key

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The full key is used to call the gateway and stays in this tab — never sent to orbit or saved.

About this endpoint

What it does

Checks whether two colors have enough contrast to be readable, using the WCAG accessibility guidelines. Send a foreground (text) color and a background color as hex codes, and get back the contrast ratio from 1 to 21 and whether it passes WCAG AA, AAA and AA for large text. Use it in design tools, theme builders and accessibility audits.

Request Body

Parameter	Type	Mandatory	Description
foreground	String	Yes	Foreground color as a hex code, e.g. `#000` or `#000000`. `rgb()` and color names are not supported.
background	String	Yes	Background color as a hex code, e.g. `#fff` or `#ffffff`. `rgb()` and color names are not supported.

Response

A successful call returns a JSON object with these fields:

Parameter	Type	Description
tool	String	Name of the tool that produced the response.
ratio	Number	Contrast ratio between the two colors, from 1 to 21.
aa	Boolean	`true` if the ratio meets WCAG AA for normal text (4.5 or higher).
aaa	Boolean	`true` if the ratio meets WCAG AAA for normal text (7 or higher).
aaLarge	Boolean	`true` if the ratio meets WCAG AA for large text (3 or higher).
error	String	Error message. Present only when the input is invalid, e.g. "Invalid hex color".

If a color is not a valid hex code, the API returns {"error":"Invalid hex color"}.

▣ ENDPOINT 02 / 02

POST

Hex, RGB & HSL Color Converter

https://api.eu.apyhub.com/freedailypro/color-contrast-conversion-api/design/color-convert

QUICKSTART

GUIDE

Quickstart

Convert a color by sending the RGB or hex values in a JSON body.

curl -X POST "https://api.eu.apyhub.com/freedailypro/color-contrast-conversion-api/design/color-convert" \
  -H "apy-token: $APY_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"hex":"#1e90ff"}'

What you'll get back

The live response to the request above:

{
  "tool": "Color converter client and server side from freedailypro",
  "hex": "#1e90ff",
  "rgb": {
    "r": 30,
    "g": 144,
    "b": 255
  },
  "hsl": {
    "h": 210,
    "s": 100,
    "l": 55.9
  }
}

TRY ITLIVE · 10 ATOMS

API key

Loading your default key…

The full key is used to call the gateway and stays in this tab — never sent to orbit or saved.

About this endpoint

What it does

Converts a color between hex, RGB and HSL. Send either a hex code (such as #FF5733) or r, g and b values from 0 to 255, and get the same color back in all three formats. If both are sent, hex is used. Use it in design tools, theme builders and CSS generators.

Request Body

Parameter	Type	Mandatory	Description
b	Number	No	Blue channel value. Must be between 0 and 255.
g	Number	No	Green channel value. Must be between 0 and 255.
r	Number	No	Red channel value. Must be between 0 and 255.
hex	String	No	Hex color string.

Response

A successful call returns a JSON object with these fields:

Parameter	Type	Description
tool	String	Name of the tool that produced the response.
hex	String	Color as a hex code, e.g. `#FF5733`.
rgb	Object	Color as RGB values.
rgb.r	Number	Red channel, 0–255.
rgb.g	Number	Green channel, 0–255.
rgb.b	Number	Blue channel, 0–255.
hsl	Object	Color as HSL values.
hsl.h	Number	Hue in degrees, 0–360.
hsl.s	Number	Saturation in percent, 0–100.
hsl.l	Number	Lightness in percent, 0–100.

▣ COMMON ERRORS

Errors any endpoint can return

400bad_request

Required parameter missing or malformed body.

401unauthorized

API key missing, revoked, or not authorized for this service.

429rate_limited

Your plan's per-second rate exceeded. Retry with exponential backoff.

503upstream_busy

Backend temporarily unavailable. Try again in a few seconds.

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