ToolVet
78trust / 100

Commerce Changed

by Forest Gas Station in Developer tools

x402 APIPassing, checked 37 min ago

Cheaply detect material public product changes in price, availability, selected variant or seller using a deterministic hash. Timestamps, images and analytics noise are excluded.

POST
https://http--forest-gas-station--lcjl27p8lmjs.code.run/commerce/changed
Price
$0.001
per call in USDC
Uptime
100%
last 30 days
Response time
117 ms
252 ms slowest 5%
Last check
Passed
37 min ago, next any minute now

Run a free test callHow to call it

Reliability

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Status and outage history · Atom feed · Watch with other listings

How to call it

POST https://http--forest-gas-station--lcjl27p8lmjs.code.run/commerce/changed

Each call costs $0.001 in USDC on Base Sepolia, paid with the request over x402.

Run a free test callOne unpaid request, the way an agent sends it. You see the payment challenge it gets back. Nothing is charged.

Example request

From the listing.

POST https://http--forest-gas-station--lcjl27p8lmjs.code.run/commerce/changed
content-type: application/json

{
  "previous_hash": "sha256:0000000000000000000000000000000000000000000000000000000000000000",
  "url": "https://shop.example/products/widget"
}

Parameters

ParameterTypeRequiredDescription
previous_hashstringNo
urlstringYes

Example response

The provider's example. We can't check it without paying.

{
  "capability": "commerce.changed",
  "data": {
    "changed": false,
    "changed_fields": [],
    "current_summary": {},
    "new_hash": "example",
    "previous_hash": "example"
  },
  "meta": {
    "cache": "miss",
    "checked_at": "2026-01-01T00:00:00.000Z",
    "duration_ms": 0,
    "provider": "state-hash"
  },
  "ok": true,
  "version": "1"
}

Call it from code

The curl command shows the payment challenge. The JavaScript and Python versions pay and call, and never pay more than $0.001.

curl: see the payment challenge
# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i -X POST 'https://http--forest-gas-station--lcjl27p8lmjs.code.run/commerce/changed' \
  -H 'content-type: application/json' \
  --data-raw '{"previous_hash":"sha256:0000000000000000000000000000000000000000000000000000000000000000","url":"https://shop.example/products/widget"}'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - -X POST 'https://http--forest-gas-station--lcjl27p8lmjs.code.run/commerce/changed' \
  -H 'content-type: application/json' \
  --data-raw '{"previous_hash":"sha256:0000000000000000000000000000000000000000000000000000000000000000","url":"https://shop.example/products/widget"}' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode
JavaScript: pay and call
// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.001 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.001" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.001 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fhttp--forest-gas-station--lcjl27p8lmjs.code.run%2Fcommerce%2Fchanged&method=POST
const res = await pay("https://http--forest-gas-station--lcjl27p8lmjs.code.run/commerce/changed", {
  method: "POST",
  headers: { "content-type": "application/json" },
  body: JSON.stringify({
    "previous_hash": "sha256:0000000000000000000000000000000000000000000000000000000000000000",
    "url": "https://shop.example/products/widget"
  }),
});
console.log(res.status, await res.text());
Python: pay and call
# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.001 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.001"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.post(
        "https://http--forest-gas-station--lcjl27p8lmjs.code.run/commerce/changed",
        json={
            "previous_hash": "sha256:0000000000000000000000000000000000000000000000000000000000000000",
            "url": "https://shop.example/products/widget",
        },
    )
    print(res.status_code, res.text)

Security scan

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