# Extract PDF Links as JSON - Change Watch

> Extract PDF Links as JSON - Change Watch is a paid API for AI agents from page.intel.rallylive.ca, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-20).

Monitors a webpage's PDF links for changes, returning current PDF link data, a changed flag, before/after diffs, and last-seen timestamp.

## Facts

- Endpoint: GET https://page.intel.rallylive.ca/watch/page/pdf-links/json?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/extract-pdf-links-as-json-change-watch-3fdb7d4f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_rfZyRhVVBOHkXm-oyPsZA

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 extract-pdf-links-as-json-change-watch-3fdb7d4f
```

Example prompt: Keep an eye on the PDF links on https://example.gov/publications and let me know if anything changes — new PDFs added, old ones removed, or links updated.

## When to prefer this

Choose this endpoint when you need to track whether the PDF links on a specific webpage have changed over time, particularly for scheduled monitoring or alerting workflows. It is distinct from a one-shot PDF link extractor because it stores and compares state across calls (up to 90 days), returning a structured diff. Prefer it over generic page-change monitors when you specifically care about PDF link additions, removals, or URL changes rather than full page content.

## Known failure modes

- Target URL is unreachable or returns an error — check may fail or return stale data
- No previous check stored for this URL (first call) — 'changed' will be null or baseline with no diff
- PDF links are embedded in JavaScript and not present in static HTML — extraction may be incomplete
- URL redirects or page structure changes significantly between calls — false positives in diff
- 90-day retention window exceeded — previous snapshot lost, baseline resets

## How this service works

Change watch for extract pdf links as json: runs the check, compares it with the result from your previous call for the same url (kept 90 days) and returns the current answer, changed true/false, the fields that changed with before/after values, and when it was last seen. Schedule it to be alerted when this changes. $0.02 per check.

## Output

Returns a JSON object containing: the current list of PDF links extracted from the page, a boolean 'changed' field indicating whether the links differ from the previous check, an array of changed fields with before and after values showing exactly what was added, removed, or modified, and a timestamp of when the page was last seen. Previous check results are retained for 90 days.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/extract-pdf-links-as-json-change-watch-3fdb7d4f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from page.intel.rallylive.ca](https://www.zero.xyz/host/page.intel.rallylive.ca/llms.txt)