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Web Monitor – Deterministic Website Change Detection
x402
Web Monitor – Deterministic Website Change Detection is a paid API for AI agents from x402-gateway-production-1f21.up.railway.app, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-11).
Fetches a webpage, hashes its content (optionally scoped to a CSS selector), and compares against a previous hash to deterministically detect changes.
Price / call$0.005
Success—
StatusUnknown
How this service works
Machine-payable x402 utilities for hashing, Base64, UUID generation, unit and timezone conversion, realtime crypto market data, webpage/document extraction, URL-to-Markdown, metadata, RAG ingestion and deterministic website change detection.
Output
Returns a JSON object indicating whether the page content has changed (compared to the provided previous hash), along with the new hash of the current content. If no previous hash is provided, returns the current hash for future comparisons. The status field indicates readiness or change outcome.
Example use cases
Track documentation page for updates
“Monitor https://docs.stripe.com/api/changes for me — compare it against the hash b7e2a1f3d94c...88f2 I saved last week and let me know if anything in the #release-notes section has changed. Give me up to 45 seconds to fetch it.”
Watch competitor pricing page
“Has https://competitor.com/pricing changed since yesterday? Use the previous hash 9a4c2b1d...f3e7 to check, and ignore the nav and footer — just look at the .pricing-table section.”
Detect government regulation page changes
“Check https://regulations.gov/document/some-rule-page for any content changes compared to hash c1d2e3f4...a0b1, and give it up to 20 seconds to load — I need to know if the rule text has been updated.”
Technical details
Endpoint
POSThttps://x402-gateway-production-1f21.up.railway.app/web/monitor?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need deterministic, hash-based change detection on a specific webpage or a subsection of it (via CSS selector). It is ideal for polling workflows where you want a cheap, repeatable signal that a page has or has not changed, without parsing or interpreting the content. Prefer it over full-text extraction endpoints when you only need a yes/no changed signal rather than the actual page content.
Side effects
- URL is unreachable or returns a non-200 status — fetch fails with an error
- Timeout exceeded (>60 seconds) — request rejected before content is retrieved
- Invalid previous_hash format (not 64 hex characters) — schema validation error
- CSS selector matches nothing on the page — hash may reflect empty content
- Malformed URL — rejected by URI format validation
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"status": "ready"
}
}Tags
x402
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