CSS named color lookup

Two-way CSS named color tool. Pass a name (e.g. "rebeccapurple") to get its canonical RGB/hex; pass a hex/rgb color to get the closest CSS named color and the distance (RGB Euclidean, 0 = exact match). Useful when an agent needs to convert designer-speak into code, or surface a human-friendly handle for an arbitrary color (e.g. "that's basically dodgerblue").

Input

Field	Type	Description
color *	string	A CSS color name OR any hex/rgb/hsl/oklch color to find the nearest name for.

Example output

{
  "input": "#6a5acd",
  "isNamed": true,
  "name": "slateblue",
  "distance": 0,
  "hex": "#6a5acd",
  "rgb": {
    "r": 106,
    "g": 90,
    "b": 205
  }
}

Try it — see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/color-name \
  -H "Content-Type: application/json" \
  -d '{"color":"#6a5acd"}'

The response is HTTP 402 Payment Required with exact payment requirements. Any x402 v2 client pays automatically and retries:

Paid call (JavaScript agent)

import { wrapFetchWithPayment } from "@x402/fetch";
import { x402Client } from "@x402/core/client";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

const client = new x402Client();
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/color-name", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "color": "#6a5acd"
  }),
});

No wallet? Pay with compute

This is a pure-CPU tool, so an agent without a wallet can pay with proof-of-work instead of USDC: fetch a challenge, solve the sha256 puzzle (16 leading zero bits — a fraction of a second of CPU, no money, no AI tokens), and resend with the X-Pow-Solution header.

import { createHash } from "node:crypto";
const lz = (b) => { let t = 0; for (const x of b) { if (!x) { t += 8; continue; } t += Math.clz32(x) - 24; break; } return t; };
const c = await (await fetch("https://agent402.tools/api/pow/challenge?slug=color-name")).json();
let n = 0;
while (lz(createHash("sha256").update(c.challenge + ":" + n).digest()) < c.difficulty) n++;
await fetch("https://agent402.tools/api/color-name", { method: "POST", headers: { "X-Pow-Solution": c.token + ":" + n, "Content-Type": "application/json" }, body: JSON.stringify({"color":"#6a5acd"}) });

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