URL unshortener

Follow a short link's redirect chain (bit.ly, t.co, youtu.be, tracking links, …) without downloading any page body: returns the final URL, the final HTTP status, and every hop with its status code and Location target. Send POST /api/unshorten-url with the required field url and pay $0.002 per call over x402 or MPP (there is no free tier). It returns a JSON object with url, finalUrl, finalStatus, redirects, truncated and 1 more.

Capped at 5 redirects; every hop is SSRF-re-validated, so chains that dive into private networks are blocked. Lets agents pre-flight links before fetching or citing them.

Category: Web & documents · Tags: web url redirect unshorten short-link safety preflight

TRY IN PLAYGROUND →

Parameters

Example request

curl -i -X POST https://agent402.tools/api/unshorten-url \
  -H "Content-Type: application/json" \
  -d '{"url":"https://www.agent402.tools/"}'

Without payment this returns HTTP 402 Payment Required with the exact price for unshorten-url; any x402 v2 or MPP client pays it and retries.

Example response

{
  "url": "https://www.agent402.tools/",
  "finalUrl": "https://agent402.tools/",
  "finalStatus": 200,
  "redirects": 1,
  "truncated": false,
  "hops": [
    {
      "url": "https://www.agent402.tools/",
      "status": 301,
      "location": "https://agent402.tools/"
    },
    {
      "url": "https://agent402.tools/",
      "status": 200,
      "location": null
    }
  ]
}

From an MCP client

catalog.call {
  "slug": "unshorten-url",
  "params": {
    "url": "https://www.agent402.tools/"
  }
}

The hosted connector at https://agent402.tools/mcp needs a payment for unshorten-url; the stdio package pays it from a wallet or from AGENT402_CREDITS_KEY. Local install: npx -y agent402-mcp.

Errors and behavior

• url is required. An input the tool rejects returns an HTTP 4xx whose body carries error, tool, expected, required and example, so the caller can correct it.
• A paid call that ends in any status of 400 or above is not charged over x402, MPP or a prepaid credits key: settlement is cancelled when the tool fails. The exception is a Tempo push credential, a transfer the buyer sent before the call: it settles before the tool runs, so if the tool then fails the payment is recorded as a refund owed to the paying wallet.
• Wallet-only: this tool reaches the network or stored state, so it has no proof-of-work tier. A prepaid card-credits key issued earlier (Authorization: Bearer a402_...) also pays it.
• A GET or HEAD to /api/unshorten-url returns the same 402 quote, so the price can be read without a body.
• An Idempotency-Key header makes a retried paid call replay the first 200 instead of charging again (an answer larger than 1 MB is not replayed).

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();
client.setSpendControls?.(false); // keep your own spending ceiling in code
registerExactEvmScheme(client, { signer: privateKeyToAccount(KEY) });
const payFetch = wrapFetchWithPayment(fetch, client);

const res = await payFetch("https://agent402.tools/api/unshorten-url", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({
    "url": "https://www.agent402.tools/"
  }),
});

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