Color palette generator

Generate a coordinated palette from a base color using a named color-theory scheme: complementary (2 colors), analogous (3), triadic (3), tetradic (4), split-complementary (3), or monochromatic (5 lightness variants). Returns each color in hex, rgb, hsl, and oklch so the agent can drop them straight into any framework. Hue rotation happens in HSL — matches Adobe Color / Coolors expectations, not perceptual Oklab geometry.

Input

Field	Type	Description
color *	string	Base color (any notation parseColor accepts).
scheme *	string	One of: complementary, analogous, triadic, tetradic, split-complementary, monochromatic.

Example output

{
  "base": "#1d4ed8",
  "scheme": "triadic",
  "colors": [
    {
      "hex": "#1d4ed8",
      "hsl": {
        "h": 224.04,
        "s": 76.42,
        "l": 48.04
      }
    },
    {
      "hex": "#d81d4e",
      "hsl": {
        "h": 344.04,
        "s": 76.42,
        "l": 48.04
      }
    },
    {
      "hex": "#4ed81d",
      "hsl": {
        "h": 104.04,
        "s": 76.42,
        "l": 48.04
      }
    }
  ]
}

Try it — see the 402 challenge (free)

curl -i -X POST https://agent402.tools/api/color-palette \
  -H "Content-Type: application/json" \
  -d '{"color":"#1d4ed8","scheme":"triadic"}'

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-palette", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "color": "#1d4ed8",
    "scheme": "triadic"
  }),
});

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-palette")).json();
let n = 0;
while (lz(createHash("sha256").update(c.challenge + ":" + n).digest()) < c.difficulty) n++;
await fetch("https://agent402.tools/api/color-palette", { method: "POST", headers: { "X-Pow-Solution": c.token + ":" + n, "Content-Type": "application/json" }, body: JSON.stringify({"color":"#1d4ed8","scheme":"triadic"}) });

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