# Page Change Detection

> Page Change Detection is a paid API for AI agents from intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-14).

Hashes the readable text of a webpage and compares it with the previously stored version to detect changes, reporting word delta, similarity score, and sample of added/removed lines.

## Facts

- Endpoint: GET https://intel.rallylive.ca/site/change-detect
- 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/page-change-detection-fe67b08b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_rBT-16kOxTLFmECYIAVQu

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 page-change-detection-fe67b08b
```

Example prompt: Check if the page at https://acme.com/pricing has changed since the last time you checked it, and tell me how much it changed — show me any lines that were added or removed.

## When to prefer this

Choose this endpoint when you need lightweight, cost-effective change detection on a specific webpage without storing full page archives. It is ideal for monitoring competitor pages, documentation, listings, or any public URL where you only need to know if the readable text changed and by how much, rather than capturing full page structure or screenshots.

## Known failure modes

- URL is unreachable or returns a non-200 status — no comparison possible
- First-time call has no previous snapshot to compare against — baseline is stored, no diff reported
- Page content is JavaScript-rendered and not statically readable — hash may be empty or incomplete
- Snapshot older than 90 days has expired — treated as a new baseline
- Invalid or malformed URL input — request rejected

## How this service works

Page change detection: hashes the readable text of a page and compares with the version from your previous call (kept 90 days). Reports whether it changed, how much (word delta and similarity), and a sample of added/removed lines. Watch competitor pages, docs or listings. $0.01 per check.

## Output

Returns whether the page text has changed since the previous call, a similarity score, the word count delta (words added vs removed), and a sample of specific lines that were added or removed. The previous snapshot is 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/page-change-detection-fe67b08b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from intel.rallylive.ca](https://www.zero.xyz/host/intel.rallylive.ca/llms.txt)