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x402 Gateway Webpage Change Detector
x402
x402 Gateway Webpage Change Detector is a paid API for AI agents from x402-gateway-production-1f21.up.railway.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-12).
Fetches a webpage, computes a deterministic hash of its content, and returns a diff against a previous version to detect meaningful changes in prices, docs, policies, availability, or competitor pages.
Price / call$0.001
Success—
StatusUnknown
How this service works
Detect whether a webpage changed. Website change detection and recurring webpage monitoring for price changes, inventory changes, availability changes, documentation updates, policy updates and competitor monitoring. Compare current content with previous_hash or previous_text and return current_hash plus deterministic change status and diffs.
Output
Returns a structured response containing a deterministic hash of the current page content, a boolean indicating whether content changed, a character-level diff showing what was added or removed relative to the previous version, and optionally the full current extracted text — all filtered to the specified CSS selector if provided.
Example use cases
Competitor price monitoring
“Check whether the pricing page at https://competitor.com/pricing has changed since last week — compare against hash 'e3b0c44298fc' and only scan the .price-card section, ignoring the nav and footer.”
Terms of service change alert
“Has the terms of service page at https://platform.com/legal/tos changed at all? Here's the previous hash: 'da39a3ee5e6b' — show me what's different if there are any changes.”
Product availability tracking
“Check if the product page at https://store.example.com/product/widget-pro is showing any new availability or stock info — compare against this previous text snapshot and tell me what changed, focusing on the .stock-status section.”
Technical details
Endpoint
POSThttps://x402-gateway-production-1f21.up.railway.app/change?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need deterministic, hash-based change detection on a specific webpage or a CSS-targeted section of it — especially for price monitoring, policy tracking, documentation updates, or competitor intelligence. Unlike generic scrapers, it provides structured diffs and hashes designed for automated comparison workflows, making it ideal for agents that need to decide 'has this changed?' without storing full page snapshots themselves.
Side effects
- URL unreachable or returns non-200 status — endpoint returns error with HTTP status code
- Timeout exceeded (configurable 5–60 seconds) if the target page loads slowly
- Invalid CSS selector causes empty content extraction
- Previous hash or text mismatch results in full diff returned
- max_diff_chars or max_text_chars limits truncate large page content
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"url": "https://example.com/",
"status": "ready",
"current_hash": "example",
"comparison_status": "baseline"
}
}Tags
x402
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