Page Metadata API

POST /v1/page-metadata
content-type: application/json
payment-signature: <base64 x402 payload>

{
  "url": "https://grist.tools/samples/web/render-article.html"
}

200 OK
payment-response: <base64 settlement receipt>

{
  "url": "https://grist.tools/samples/web/render-article.html",
  "source_url": "https://grist.tools/samples/web/render-article.html",
  "final_url": "https://grist.tools/samples/web/render-article.html",
  "http_status": 200,
  "title": "Measuring Rainfall with a Simple Gauge",
  "description": "A short guide to reading a cylinder rain gauge at the same hour every day.",
  "canonical": "https://grist.tools/samples/web/render-article.html",
  "lang": "en",
  "hreflang": [
    {
      "lang": "en",
      "href": "https://grist.tools/samples/web/render-article.html"
    },
    {
      "lang": "x-default",
      "href": "https://grist.tools/samples/web/render-article.html"
    }
  ],
  "hreflang_total": 2,
  "hreflang_truncated": false,
  "favicon": "https://grist.tools/favicon.png",
  "charset": "utf-8",
  "opengraph": {
    "title": "Measuring Rainfall with a Simple Gauge",
    "description": "Read the gauge at eye level, at the same hour, and write the number down.",
    "image": "https://grist.tools/og.png",
    "type": "article",
    "site_name": "Grist Samples",
    "url": "https://grist.tools/samples/web/render-article.html"
  },
  "twitter": {
    "card": "summary_large_image",
    "title": "Measuring Rainfall with a Simple Gauge",
    "description": "Read the gauge at eye level, at the same hour, and write the number down.",
    "image": "https://grist.tools/og.png"
  },
  "robots_meta": "index, follow",
  "fetched_at": "2026-09-01T12:00:00.000Z"
}

// page-metadata: $0.002 per call, paid in USD Coin on eip155:8453 via x402
// Install: npm install @x402/fetch@2 @x402/evm@2 viem@2
// Save as client.mjs (ES module, Node 18+), export EVM_PRIVATE_KEY with the paying wallet's key in your shell, then run: node client.mjs
// The wrapper reads the 402 (payment-required), signs and retries with payment-signature.
import { wrapFetchWithPayment, x402Client, decodePaymentResponseHeader } from '@x402/fetch'
import { ExactEvmScheme } from '@x402/evm/exact/client'
import { privateKeyToAccount } from 'viem/accounts'

const account = privateKeyToAccount(process.env.EVM_PRIVATE_KEY)
const client = new x402Client().register('eip155:8453', new ExactEvmScheme(account))
const fetchWithPayment = wrapFetchWithPayment(fetch, client)

const body = {
  "url": "https://grist.tools/samples/web/render-article.html"
}

const res = await fetchWithPayment('https://grist.tools/v1/page-metadata', {
  method: 'POST',
  headers: { 'content-type': 'application/json' },
  body: JSON.stringify(body),
})
console.log(res.status, await res.json())
const settle = res.headers.get('payment-response')
if (settle) console.log(decodePaymentResponseHeader(settle).transaction)

# page-metadata: $0.002 per call, paid in USD Coin on eip155:8453 via x402
# Install: pip install "x402[requests,evm]>=2.24,<3"
# The session reads the 402 (payment-required), signs and retries with payment-signature.
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http import decode_payment_response_header
from x402.http.clients.requests import x402_requests
from x402.mechanisms.evm.exact import register_exact_evm_client
from x402.mechanisms.evm.signers import EthAccountSigner

account = Account.from_key(os.environ["EVM_PRIVATE_KEY"])
client = x402ClientSync()
register_exact_evm_client(client, EthAccountSigner(account), networks="eip155:8453")
session = x402_requests(client)

payload = {
    "url": "https://grist.tools/samples/web/render-article.html"
}

res = session.post("https://grist.tools/v1/page-metadata", json=payload)
print(res.status_code, res.json())
settle = res.headers.get("payment-response")
if settle:
    print(decode_payment_response_header(settle).transaction)

# page-metadata: $0.002 per call, paid in USD Coin on eip155:8453 via x402
# 1. Unpaid call: HTTP 402, the requirements in the payment-required header (base64 JSON) and in the body.
curl -i -X POST 'https://grist.tools/v1/page-metadata' -H 'content-type: application/json' -d '{"url":"https://grist.tools/samples/web/render-article.html"}'

# 2. Same call with the signed payment (an EIP-3009 authorization, EIP-712 signed: it cannot be
#    typed by hand). x-payment is accepted as the v1 alternative. HTTP 200 carries payment-response.
curl -i -X POST 'https://grist.tools/v1/page-metadata' -H 'content-type: application/json' -H 'payment-signature: <base64 x402 payload>' -d '{"url":"https://grist.tools/samples/web/render-article.html"}'