# Canonical URL Declarations — Literal Attribute Matches

> Canonical URL Declarations — Literal Attribute Matches is a paid API for AI agents from market.datapackvibe.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-30).

Parses a web page (by URL or raw HTML) to find canonical link elements whose specified attribute exactly matches a given value, returning matched results filtered by a search term.

## Facts

- Endpoint: POST https://market.datapackvibe.com/x402/assistant-bx-web-canonical-attribute-match?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/canonical-url-declarations-literal-attribute-matches-28e1ab9c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_eC4C7958GxEnNgrjEFw-q

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-literal-attribute-matches-28e1ab9c -d '<json body>'
```

Example prompt: Check the page at https://example.com/products and find all canonical link elements where the attribute 'id' exactly matches 'main-canonical', filtering results for the term 'product'.

## When to prefer this

Choose this endpoint when you need to statically parse a single page's canonical link declarations and filter by an exact attribute value match — ideal for SEO audits, canonical tag verification, or scraping canonical href values without JavaScript execution. Prefer this over full-page scraping tools when your goal is specifically canonical URL metadata, and over general HTML parsers when you need the preset logic for canonical declarations with attribute filtering already built in.

## Known failure modes

- URL is unreachable or returns non-200 status — no results returned
- Page requires JavaScript rendering — canonical tags injected by JS will not be found
- HTML provided is malformed or exceeds 100,000 character limit — parse error
- Attribute name fails regex validation (must start with letter, alphanumeric/colon/underscore/hyphen only) — validation error
- No canonical elements match the given attribute value — empty result set
- Term or attribute_value exceed length limits — request rejected

## How this service works

Canonical URL declarations — Literal attribute matches: Literal attribute matches 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 literal attribute matches result.

## Output

Returns a bounded set of canonical link element matches where the specified attribute exactly equals the given value, filtered by the search term. Each result reflects a literal attribute match found in the static HTML of the page (no JavaScript rendering). Results are scoped to one page fetch and include the matched canonical href and relevant attribute data.

## 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-literal-attribute-matches-28e1ab9c/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)