Structured Data Extraction API

x402 pay per call

$0.02 per successful call, paid in USDC on Base. No account or API key required. The live PAYMENT-REQUIRED header quotes the authoritative price.

curl request

curl -i -X POST 'https://api.fastaf.co/x402/v1/extract' \
  -H 'Content-Type: application/json' \
  -d '{"url":"https://books.toscrape.com/catalogue/a-light-in-the-attic_1000/index.html","schema":{"type":"object","required":["title","price","in_stock"],"properties":{"title":{"type":"string"},"price":{"type":"object","required":["amount","currency"],"properties":{"amount":{"type":"number"},"currency":{"type":"string"}}},"in_stock":{"type":"boolean"}}}}'

Example 402 payment challenge

Illustrative recipient address, not a payment destination. Request a fresh challenge, sign it with an x402 v2 client and retry the same URL with PAYMENT-SIGNATURE. The header is base64 JSON v2; the compatibility body uses v1 aliases on Base. Only successful results settle.

HTTP/1.1 402 Payment Required
Content-Type: application/json
PAYMENT-REQUIRED: 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

{
  "error": "payment_required",
  "x402Version": 2,
  "resource": {
    "url": "https://api.fastaf.co/x402/v1/extract",
    "description": "Structured data extraction (JSON Schema)",
    "mimeType": "application/json"
  },
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:8453",
      "amount": "20000",
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "payTo": "0x1111111111111111111111111111111111111111",
      "maxTimeoutSeconds": 300,
      "extra": {
        "name": "USD Coin",
        "version": "2"
      }
    }
  ]
}

Decoded PAYMENT-REQUIRED header

{
  "x402Version": 2,
  "resource": {
    "url": "https://api.fastaf.co/x402/v1/extract",
    "description": "Structured data extraction (JSON Schema)",
    "mimeType": "application/json"
  },
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:8453",
      "amount": "20000",
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "payTo": "0x1111111111111111111111111111111111111111",
      "maxTimeoutSeconds": 300,
      "extra": {
        "name": "USD Coin",
        "version": "2"
      }
    }
  ]
}

JSON discovery response example

JSON that validates against the request schema, minified. Optional schema fields may be missing or null; only fields listed in required are guaranteed to be present in a successful response. Optional nulls are omitted before validation. Answers that are not JSON, do not match the schema or exceed 64 KB return 422 extraction_failed with validation_errors and are never charged or settled. This example is illustrative.

{
  "title": "A Light in the Attic",
  "price": {
    "amount": 51.77,
    "currency": "GBP"
  },
  "in_stock": true
}

Response with an API key

The same data over REST with a prepaid key. The JSON body is the example above; failed requests are not charged.

curl -X POST 'https://api.fastaf.co/v1/extract' \
  -H "Authorization: Bearer $FASTAF_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{"url":"https://books.toscrape.com/catalogue/a-light-in-the-attic_1000/index.html","schema":{"type":"object","required":["title","price","in_stock"],"properties":{"title":{"type":"string"},"price":{"type":"object","required":["amount","currency"],"properties":{"amount":{"type":"number"},"currency":{"type":"string"}}},"in_stock":{"type":"boolean"}}}}'

MCP tools

extract MCP tool calls require an API key or OAuth; x402 payments apply to HTTP data calls.

Full endpoint reference for agents

Pricing

x402: $0.02 per successful call, USDC on Base, no account. API key: 40 credits per request from one-time credit packs, without expiry. Credit packs are shared by every endpoint and never renew.

Free: 500 credits every month after email verification, no card. See pricing. Alternatives: FastAF vs SerpApi, vs toll402, vs serp402, vs AgentBIT, vs Amazon PA-API.

Parameters

Response fields

• application/json
• your schema’s fields
• 422 extraction_failed
• validation_errors

Passing these fields to an LLM? See token-aware scraping: only what your LLM needs.

Asking for fields instead of a whole page is how you reduce tokens with structured extraction; the docs show it next to Markdown output and result caps.

Guides

• Add FastAF to Claude Code, Codex and Cursor

  One remote MCP server, three clients: the claude, codex and Cursor mcp.json setup for https://api.fastaf.co/mcp, with the API key auth it really uses.

FAQ

Other APIs

• Web Scraping API

  Public pages in selectable formats

• Screenshot API

  Full-page or viewport screenshots

• Google SERP API

  Structured web search results

• Google Maps API

  Place search and place details

All APIs → · Guides and benchmarks on the blog →