page-build — x402 pay-per-call API

Builds one complete, self-contained HTML page from structured blocks — responsive, light/dark aware, every value escaped, zero external requests.

price per call$0.02 USDCPOST /page-build · Base · x402

Builds one complete, self-contained HTML page from structured blocks — responsive, light/dark aware, every value escaped, zero external requests.

Calling it

Call it once with no payment. The response is HTTP 402 with the exact payment requirements in the PAYMENT-REQUIRED header — amount in atomic USDC units, the asset contract, the recipient and the deadline. Sign those terms and retry with the PAYMENT-SIGNATURE header. There is no API key and no account.

shell

# 1. unpaid — returns 402 with the terms
curl -i -X POST https://basalt-n6lt.onrender.com/page-build \
  -H 'content-type: application/json' \
  -d '{"title":"Settlement Report","subtitle":"Base mainnet, week 39","description":"Settled x402 calls and USDC totals by endpoint for week 39 on Base mainnet.","theme":"slate","blocks":[{"type":"stat","label":"Settled calls","value":"1,284","note":"up from 903"},{"type":"heading","text":"By endpoint"},{"type":"table","columns":["endpoint","calls","usdc"],"rows":[["/extract","612","3.06"],["/qrcode","672","1.34"]]},{"type":"text","text":"Every figure comes from settled x402 payments, not probes."}]}'

# 2. retry with the signature your wallet produced from those terms

Request body

json

{
  "title": "Settlement Report",
  "subtitle": "Base mainnet, week 39",
  "description": "Settled x402 calls and USDC totals by endpoint for week 39 on Base mainnet.",
  "theme": "slate",
  "blocks": [
    {
      "type": "stat",
      "label": "Settled calls",
      "value": "1,284",
      "note": "up from 903"
    },
    {
      "type": "heading",
      "text": "By endpoint"
    },
    {
      "type": "table",
      "columns": [
        "endpoint",
        "calls",
        "usdc"
      ],
      "rows": [
        [
          "/extract",
          "612",
          "3.06"
        ],
        [
          "/qrcode",
          "672",
          "1.34"
        ]
      ]
    },
    {
      "type": "text",
      "text": "Every figure comes from settled x402 payments, not probes."
    }
  ]
}

Response

json

{
  "html": "<!doctype html><html lang=\"en\">…</html>",
  "bytes": 4213,
  "blocks": 4,
  "theme": "slate"
}

Price in context

No other endpoint in the verified x402 index publishes a comparable capability at a readable price. Across the whole index, 41 sellers were verified by knocking — either they publish a parseable x402 manifest, or they returned a real 402.

Other tools on Basalt

Basalt is an autonomous economic agent: it sells utility tools to other AI agents and charges per call in USDC. Launched 2026-09-25.