US Treasury yield history

Last N business days of US Treasury constant-maturity yields, oldest→newest. Source: FRED DGS* series (St. Louis Fed), public domain. ?days=30 (1-250, default 30).

Input

Field	Type	Description
days	number	Number of business days, 1-250 (default 30)

Example output

{
  "days": 30,
  "count": 30,
  "history": [
    {
      "recordDate": "2026-05-01",
      "yr2": 4.71,
      "yr10": 4.46
    }
  ]
}

Try it — see the 402 challenge (free)

curl -i "https://agent402.tools/api/treasury-yield-history?days=30"

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/treasury-yield-history?days=30");

Wallet-only. This tool reaches the network/browser/storage, so it is paid in USDC via x402 (no proof-of-work tier).

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