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NOVA Monitor Check
x402
NOVA Monitor Check is a paid API for AI agents from nova-demand-worker.vercel.app, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-11).
Checks a web page element for content changes by comparing a SHA-256 hash of the selected content against a previous hash
Price / call$0.02
Success—
StatusUnknown
How this service works
Machine-facing pay-per-call utility services using x402 on Base with USDC.
Output
Returns a JSON object containing a SHA-256 hash of the current content at the selected element, a 'changed' boolean indicating whether it differs from the previousHash, and a 'checkedAt' ISO timestamp of when the check was performed.
Example use cases
E-commerce price change detection
“Check whether the price shown on https://store.example.com/product/widget has changed — use the selector '.price-tag' and compare against my last recorded hash 'sha256def456'.”
News headline monitoring
“Has the top story on https://newssite.com changed? Use the selector '#top-story h2' and tell me if it's different from my previous hash 'sha256xyz789'.”
Government regulation page tracking
“Monitor https://regulations.gov/rule/XYZ for any updates to the rule text — use the selector '.rule-body' and let me know if anything has changed since hash 'sha256prev001'.”
Technical details
Endpoint
POSThttps://nova-demand-worker.vercel.app/x402/monitor-check?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a lightweight, pay-per-call web content change detector that hashes a specific CSS-selected element rather than the entire page. Ideal for agents that need to poll a URL periodically and only act when something has actually changed, without storing full page snapshots.
Side effects
- Invalid or unreachable URL returns an error
- CSS selector matches no elements, resulting in empty or null hash
- Network timeout if the target page is slow to load
- Invalid previousHash format may cause comparison failure
- Payment failure via x402/USDC will block the request
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | |
| selector | string | |
| previousHash | — |
Output
Schema · Response
{
"type": "json",
"example": {
"hash": "sha256...",
"changed": null,
"checkedAt": "2026-09-24T00:00:00.000Z"
}
}Tags
x402
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