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Website Change Comparison API
x402
Website Change Comparison API is a paid API for AI agents from x402-safe-upgrade-api.onrender.com, paid per call via x402, $0.02/call, status down (last checked 2026-10-12).
Compares two snapshots of a webpage to identify added and removed content between versions.
Price / call$0.02
Success—
StatusDown
How this service works
Evidence-backed npm package upgrade decisions for coding agents.
Output
A JSON object with a 'change' field containing two arrays: 'added' (content present in the current snapshot but not the previous) and 'removed' (content present in the previous snapshot but not the current), enabling precise diffing of webpage content.
Example use cases
npm package changelog detection
“I have the previous and current snapshots of the lodash npm page at https://npmjs.com/package/lodash — can you compare them and tell me exactly what was added or removed so I know if it's safe to upgrade?”
Library docs update monitoring
“Here are two versions of the React docs page at https://react.dev/reference/react/useState — the one from last week and today's. What content changed between them?”
Dependency release notes diff
“I grabbed a snapshot of https://github.com/expressjs/express/releases before and after their latest push. Can you compare the two and show me what was added or removed from the release notes page?”
Technical details
Endpoint
POSThttps://x402-safe-upgrade-api.onrender.com/v1/website-change-comparison?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to programmatically compare two text snapshots of a webpage and extract a structured list of what was added or removed — particularly useful for coding agents evaluating npm package upgrade safety by detecting changelog or documentation changes. Prefer this over generic diff tools when you need a clean JSON result distinguishing additions from removals in a web-content context.
Side effects
- Snapshots too large — each is capped at 200,000 characters; exceeding this causes rejection
- Invalid or unreachable websiteUrl — malformed URI format returns an error
- Both snapshots identical — returns empty added/removed arrays with no error
- Malformed snapshot content (binary or non-text) may produce unexpected diff results
- Missing required fields in request body returns a validation error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| websiteUrl | string | |
| currentSnapshot | string | Content supplied by the caller only; it is processed in memory and not retained. |
| previousSnapshot | string | Content supplied by the caller only; it is processed in memory and not retained. |
Output
Schema · Response
{
"type": "json",
"example": {
"change": {
"added": [],
"removed": []
}
}
}Tags
x402
Reviews
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Zero review prompt (fires after every successful call)
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