# SignalHarness Web Metadata Extractor

> SignalHarness Web Metadata Extractor is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Extracts structured web metadata (Open Graph, JSON-LD, Twitter cards, robots, icons, content type) from a given URL or raw HTML.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/web_metadata_extract/invoke
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-web-metadata-extractor-5a982beb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Al34EQfiONnQOY6yU7LPT

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability signalharness-web-metadata-extractor-5a982beb -d '<json body>'
```

Example prompt: Can you pull all the structured metadata from https://example.com — I need the Open Graph tags, JSON-LD, Twitter card info, icons, and content type?

## When to prefer this

Choose this endpoint when you need to extract all standard web metadata formats (OG, JSON-LD, Twitter cards, robots, icons) from a single URL in one call at very low cost ($0.01 USDC). Prefer it over general scraping tools when the goal is specifically structured SEO/social metadata rather than full page content, and over browser automation when you don't need JavaScript rendering.

## Known failure modes

- URL is not reachable or returns non-2xx HTTP status
- HTML content exceeds 65,536 character limit
- URL does not start with https:// (pattern validation failure)
- Page has no structured metadata — returns empty arrays for all fields
- Network timeout fetching the remote URL
- Malformed HTML that cannot be parsed cleanly — warnings array may be populated

## How this service works

Explore 330 pay-per-call x402 API services and 27 agent-native digital products, with Base USDC pricing, secure Polar checkout, and free discovery.

## Output

Returns a JSON object containing extracted structured metadata from the target webpage, including: Open Graph properties, JSON-LD objects, Twitter card tags, robots directives, page icons, content type, alternate language links, and any parsing warnings. Also includes a receipt with payment confirmation, latency, and execution details.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "pattern": "^https://",
   "maxLength": 2048,
   "minLength": 9
  },
  "html": {
   "type": "string",
   "maxLength": 65536,
   "minLength": 1
  },
  "baseUrl": {
   "type": "string",
   "pattern": "^https://",
   "maxLength": 2048,
   "minLength": 9
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "icons": [
    {
     "href": "example",
     "sizes": "example",
     "relation": "example"
    }
   ],
   "jsonLd": [
    "{\"example\":\"schema-valid caller-supplied data\"}"
   ],
   "robots": [
    "example"
   ],
   "twitter": [
    {
     "name": "example",
     "value": "example"
    }
   ],
   "warnings": [
    "Verify the caller-supplied data before relying on this result."
   ],
   "openGraph": [
    {
     "name": "example",
     "value": "example"
    }
   ],
   "contentType": "Example caller-supplied content.",
   "alternateLanguages": [
    {
     "href": "example",
     "language": "example"
    }
   ]
  },
  "status": "succeeded",
  "receipt": {
   "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
   "usage": [],
   "status": "succeeded",
   "network": "eip155:8453",
   "artifacts": [],
   "endedAtMs": 0,
   "latencyMs": 0,
   "paymentId": "example-payment",
   "receiptId": "example-receipt",
   "requestId": "example-request",
   "serviceId": "web_metadata_extract",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "10000",
   "resultSha256": "6fd2a8bfad3dba7e59252456d43728a949ecd09f865325d69489315168e8e7ad",
   "serviceVersion": "1.0.0",
   "settlementReference": "0x0000000000000000000000000000000000000000000000000000000000000000"
  },
  "artifacts": [],
  "requestId": "example-request",
  "executionId": "example-execution"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signalharness-web-metadata-extractor-5a982beb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from signalharness.ai](https://www.zero.xyz/host/signalharness.ai/llms.txt)