Use this service when you need this capability: extracts bounded document metadata, social cards, canonical links, robots directives, language alternates, icons, and JSON-LD from public HTTPS or supplied HTML.
0.01 USDC per call
x402 V2 exact payment on Base mainnet (eip155:8453) using USDC. The HTTP 402 challenge confirms the exact requirements before an authorized payment.
POST https://signalharness.ai/api/agent/services/web_metadata_extract/invokeExtracts bounded document metadata, social cards, canonical links, robots directives, language alternates, icons, and JSON-LD from public HTTPS or supplied HTML.
Documented public-source retrieval is bounded by the URL, byte, redirect, and timeout limits below. Source availability can affect execution; review the input schema and returned source metadata.
| Field | Type | Required | Limits |
|---|---|---|---|
| url | string | Optional | Pattern: ^https://; Minimum length 9; Maximum length 2048 |
| html | string | Optional | Minimum length 1; Maximum length 65536 |
| baseUrl | string | Optional | Pattern: ^https://; Minimum length 9; Maximum length 2048 |
{
"url": "https://example.com/"
}{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"additionalProperties": false,
"minProperties": 1,
"maxProperties": 2,
"required": [],
"properties": {
"url": {
"type": "string",
"pattern": "^https://",
"minLength": 9,
"maxLength": 2048
},
"html": {
"type": "string",
"minLength": 1,
"maxLength": 65536
},
"baseUrl": {
"type": "string",
"pattern": "^https://",
"minLength": 9,
"maxLength": 2048
}
}
}Illustrative output from the canonical adapter fixture and schema. It is not a completed paid execution or a current live observation.
{
"contentType": "Example caller-supplied content.",
"robots": [
"example"
],
"openGraph": [
{
"name": "example",
"value": "example"
}
],
"twitter": [
{
"name": "example",
"value": "example"
}
],
"jsonLd": [
"{\"example\":\"schema-valid caller-supplied data\"}"
],
"alternateLanguages": [
{
"language": "example",
"href": "example"
}
],
"icons": [
{
"relation": "example",
"sizes": "example",
"href": "example"
}
],
"warnings": [
"Verify the caller-supplied data before relying on this result."
]
}{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"type": "object",
"additionalProperties": false,
"minProperties": 8,
"maxProperties": 13,
"required": [
"contentType",
"robots",
"openGraph",
"twitter",
"jsonLd",
"alternateLanguages",
"icons",
"warnings"
],
"properties": {
"sourceUrl": {
"type": "string",
"minLength": 9,
"maxLength": 2048
},
"contentType": {
"type": "string",
"minLength": 3,
"maxLength": 256
},
"title": {
"type": "string",
"minLength": 1,
"maxLength": 1024
},
"description": {
"type": "string",
"minLength": 1,
"maxLength": 4096
},
"canonicalUrl": {
"type": "string",
"minLength": 1,
"maxLength": 2048
},
"language": {
"type": "string",
"minLength": 1,
"maxLength": 64
},
"robots": {
"type": "array",
"minItems": 0,
"maxItems": 128,
"items": {
"type": "string",
"minLength": 1,
"maxLength": 256
}
},
"openGraph": {
"type": "array",
"minItems": 0,
"maxItems": 128,
"items": {
"type": "object",
"additionalProperties": false,
"minProperties": 2,
"maxProperties": 2,
"required": [
"name",
"value"
],
"properties": {
"name": {
"type": "string",
"minLength": 1,
"maxLength": 256
},
"value": {
"type": "string",
"minLength": 1,
"maxLength": 8192
}
}
}
},
"twitter": {
"type": "array",
"minItems": 0,
"maxItems": 128,
"items": {
"type": "object",
"additionalProperties": false,
"minProperties": 2,
"maxProperties": 2,
"required": [
"name",
"value"
],
"properties": {
"name": {
"type": "string",
"minLength": 1,
"maxLength": 256
},
"value": {
"type": "string",
"minLength": 1,
"maxLength": 8192
}
}
}
},
"jsonLd": {
"type": "array",
"minItems": 0,
"maxItems": 32,
"items": {
"type": "string",
"minLength": 1,
"maxLength": 32768
}
},
"alternateLanguages": {
"type": "array",
"minItems": 0,
"maxItems": 128,
"items": {
"type": "object",
"additionalProperties": false,
"minProperties": 2,
"maxProperties": 2,
"required": [
"language",
"href"
],
"properties": {
"language": {
"type": "string",
"minLength": 1,
"maxLength": 64
},
"href": {
"type": "string",
"minLength": 1,
"maxLength": 2048
}
}
}
},
"icons": {
"type": "array",
"minItems": 0,
"maxItems": 128,
"items": {
"type": "object",
"additionalProperties": false,
"minProperties": 3,
"maxProperties": 3,
"required": [
"relation",
"sizes",
"href"
],
"properties": {
"relation": {
"type": "string",
"minLength": 1,
"maxLength": 64
},
"sizes": {
"type": "string",
"minLength": 0,
"maxLength": 128
},
"href": {
"type": "string",
"minLength": 1,
"maxLength": 2048
}
}
}
},
"warnings": {
"type": "array",
"minItems": 0,
"maxItems": 32,
"items": {
"type": "string",
"minLength": 1,
"maxLength": 1024
}
}
}
}Timeout: 30000 ms. Full schemas are in OpenAPI.
This schema-valid request returns the canonical HTTP 402 challenge without executing the service. A payment-capable client validates the challenge, signs only with prior authority and budget, and retries the identical body.
curl -i -X POST https://signalharness.ai/api/agent/services/web_metadata_extract/invoke \
-H "Content-Type: application/json" \
--data '{"url":"https://example.com/"}'