# Canonical URL Declarations — Distinct Value Extraction

> Canonical URL Declarations — Distinct Value Extraction is a paid API for AI agents from market.datapackvibe.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-16).

Extracts distinct (unique) values from canonical URL link elements in a static HTML page, identified by a specified attribute and attribute value.

## Facts

- Endpoint: POST https://market.datapackvibe.com/x402/assistant-bx-web-canonical-unique?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/canonical-url-declarations-distinct-value-extraction-1363ab02
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__YKNKN3n-3qH-oQseCbt9

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 canonical-url-declarations-distinct-value-extraction-1363ab02 -d '<json body>'
```

Example prompt: Can you extract the distinct canonical URL values from this HTML — look for elements with the attribute id set to 'sample': <!doctype html><html><head></head><body><link rel="canonical" href="https://www.iana.org/help/example-domains" id="sample"></body></html>

## When to prefer this

Choose this endpoint when you need to statically parse and deduplicate canonical URL declarations from a known HTML structure using a specific attribute selector, at very low cost ($0.01 per call). It is best for SEO audits, canonical tag verification, and link element inspection where JavaScript rendering is not required. Prefer alternatives if the page requires JavaScript execution or authenticated access.

## Known failure modes

- URL is behind a login wall or JavaScript rendering — static parser cannot access dynamic content
- HTML exceeds 100,000 character limit — request rejected
- No matching elements found for the given attribute/attribute value combination — empty result returned
- URL is unreachable or returns non-200 status — fetch failure
- Attribute pattern does not match schema regex — validation error

## How this service works

Canonical URL declarations — Distinct value extraction: Distinct value extraction for Canonical URL declarations. One public HTTPS page or supplied HTML; static parsing, no JavaScript rendering, login or access bypass. Specialised preset in a shared 50-profile, 20-operation engine. 0.01 USDC includes one bounded distinct value extraction result.

## Output

Returns one bounded distinct value extraction result containing the unique canonical URL values found in the specified HTML (or fetched page), filtered to elements matching the given attribute and attribute value, with duplicates removed.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "default": "",
   "maxLength": 2048
  },
  "html": {
   "type": "string",
   "default": "<!doctype html><html><head></head><body><link rel=\"canonical\" href=\"https://www.iana.org/help/example-domains\" id=\"sample\"></body></html>",
   "maxLength": 100000
  },
  "term": {
   "type": "string",
   "default": "product",
   "maxLength": 100,
   "minLength": 1
  },
  "attribute": {
   "type": "string",
   "default": "id",
   "pattern": "^[a-zA-Z][a-zA-Z0-9:_-]{0,49}$",
   "maxLength": 50
  },
  "previous_texts": {
   "type": "array",
   "items": {
    "type": "string",
    "default": "",
    "maxLength": 1000
   },
   "default": [
    "Older example"
   ],
   "maxItems": 200,
   "minItems": 0
  },
  "attribute_value": {
   "type": "string",
   "default": "sample",
   "maxLength": 200
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/canonical-url-declarations-distinct-value-extraction-1363ab02/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from market.datapackvibe.com](https://www.zero.xyz/host/market.datapackvibe.com/llms.txt)