Colour contrast check (WCAG)

$0.003 per call · failed calls are never charged · no account or API key needed

WCAG 2 contrast ratio between a text colour and a background colour, with pass/fail for AA and AAA at normal and large text sizes. Use to check that a design is readable.

Run it free (25 free calls) Buy credits by card (from $5) Example result (JSON)

Inputs

NameTypeDescription
fg (required)stringText colour
bg (required)stringBackground colour

Request

Over HTTP, with a card key from /credits:

curl -H "Authorization: Bearer adt_…" "https://agent-data-tools.revmesh2074.workers.dev/color/contrast?fg=%23767676&bg=%23ffffff"

Or one of your 25 free calls, no key:

curl "https://agent-data-tools.revmesh2074.workers.dev/color/contrast?fg=%23767676&bg=%23ffffff&trial=1"

Without a key, the same URL answers 402 Payment Required with x402 and MPP terms, so an agent with a wallet pays per call in USDC (Base, Polygon, Arbitrum, Monad, World Chain or Tempo) and retries.

Example result

{
  "ratio": 4.54,
  "aaNormal": true,
  "aaLarge": true,
  "aaaNormal": false,
  "aaaLarge": true
}

From an AI agent (MCP)

Add the MCP server to Claude, Cursor or any MCP client. This tool is color_contrast, and the first 25 successful calls are free:

https://agent-data-tools.revmesh2074.workers.dev/mcp

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