# Agent Souk – Web Page Change Detector

> Agent Souk – Web Page Change Detector is a paid API for AI agents from api.agentsouk.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-13).

Deterministically diffs a public URL against a stored snapshot and returns exactly what changed since the last check, with no LLM involvement

## Facts

- Endpoint: POST https://api.agentsouk.dev/v1/x402/lst_01M2NXY883W33X7KJCZMJ811A0?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-souk-web-page-change-detector-a8b562bc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_OF1fATSeJKgQfKhTui9AJ

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 agent-souk-web-page-change-detector-a8b562bc -d '<json body>'
```

Example prompt: Check https://store.example.com/product/widget for any changes since you last looked, and ignore lines matching "updated_at": "*" — I only care if the price or stock status changed.

## When to prefer this

Choose this endpoint when you need a deterministic, reproducible diff of a webpage or HTTP response over time without any LLM interpretation — ideal for price monitoring, changelog tracking, API response drift detection, or any workflow where exact text changes matter and hallucination risk must be zero. Prefer it over LLM-based summarization tools when you need to know precisely what bytes changed, not a paraphrase of the change.

## Known failure modes

- URL is not publicly accessible or returns a non-200 status — endpoint cannot fetch the page
- URL exceeds 2048 characters — request rejected
- URL points to a page requiring authentication — fetch fails silently or returns a login page diff
- First call for a URL establishes the baseline and returns no diff — subsequent calls show changes
- Glob patterns in ignore array are malformed — may not suppress intended lines
- reset:true wipes the stored snapshot, so the next call returns no diff and starts a new baseline

## How this service works

Tell me what changed on this page since my last check (deterministic, no LLM)

## Output

Returns a structured diff showing lines added and lines removed relative to the stored snapshot, the label echoed back, and metadata about when the snapshot was taken. No LLM is used — the comparison is byte-exact text diffing.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "format": "uri",
   "maxLength": 2048,
   "description": "Public http(s) URL to watch"
  },
  "label": {
   "type": "string",
   "maxLength": 120,
   "description": "Your own name for this watch; echoed back, not part of its identity"
  },
  "reset": {
   "type": "boolean",
   "default": false,
   "description": "Forget the stored snapshot for this target and start a fresh baseline"
  },
  "ignore": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 200
   },
   "maxItems": 5,
   "description": "Glob patterns removed before comparing (* = any run of characters on a line), e.g. \"\\\"generated_at\\\": \\\"*\\\"\""
  },
  "selector": {
   "type": "string",
   "maxLength": 200,
   "description": "Keep only lines containing this text, e.g. \"Price:\" - watch one number instead of a whole page"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-souk-web-page-change-detector-a8b562bc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.agentsouk.dev](https://www.zero.xyz/host/api.agentsouk.dev/llms.txt)