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URL Change Watch — SHA-256 Body Diff Checker
x402
URL Change Watch — SHA-256 Body Diff Checker is a paid API for AI agents from well-009-url-change-watch.mmelnyk2000.workers.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-20).
Fetches a public HTTPS URL, computes the SHA-256 hash of the response body, and reports whether the content has changed compared to a previously recorded hash or ETag.
Price / call$0.01
Success—
StatusUnknown
How this service works
Fetch a public https URL, compute SHA-256 of the response body, and report whether it changed vs a prior sha256/etag ($0.01 USDC via x402). Sticky: store sha256 and call again later. Optional previous_sha256, previous_etag, include_body_if_changed. https only — http, file, data, localhost, and private IPs rejected. Caps: 1 MB body, ~10s timeout, max 5 redirects. Returns JSON { url, final_url, content_type, byte_length, sha256, etag?, last_modified?, changed, warnings, body_preview? }. Provided as is, with no warranty or guarantee of accuracy or fitness. Nothing is stored.
Output
Returns a JSON object containing the final URL after redirects, content type, byte length, computed SHA-256 hash, optional ETag, optional Last-Modified header, a boolean 'changed' field (null if this is a baseline call with no prior hash), an array of warnings, and an optional truncated body preview (~8KB) if include_body_if_changed was true and the content changed.
Example use cases
Monitor news page for updates
“Keep an eye on https://example.com/press-releases for me — here's the SHA-256 from last time: d4e5f6a1b2c3... — has anything changed? If so, show me a preview of what's new.”
Baseline a public API response
“Fetch https://api.example.com/status and record its current SHA-256 so I can check back later to see if the response body has changed.”
Verify regulatory document hasn't changed
“Can you confirm that the document at https://regulator.example.gov/rules.pdf still matches the SHA-256 hash I have: 9f8e7d6c5b4a3...? I need to know if it's been quietly updated.”
Technical details
Endpoint
POSThttps://well-009-url-change-watch.mmelnyk2000.workers.dev/api/url-change-check?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a lightweight, stateless way to detect whether a specific public HTTPS URL's content has changed between two points in time, using SHA-256 hashing as the comparison mechanism. It is ideal when you already have a prior SHA-256 or ETag, or want to establish a baseline for future comparison. It is not suited for authenticated pages, non-HTTPS resources, large files over 1 MB, or cases where you need persistent storage of results across calls — the service is stateless and stores nothing.
Side effects
- Non-HTTPS URLs (http, file, data, localhost, private IPs) are rejected with an error
- Response body exceeds 1 MB cap — request is rejected
- Target URL times out after ~10 seconds
- More than 5 redirects encountered — request fails
- Target server returns non-200 status — reported in warnings
- SHA-256 mismatch between previous_sha256 and computed hash correctly reports changed=true but does not imply server error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| urlrequired | string | https URL to watch. http/file/data/localhost/private IPs rejected. |
| previous_etag | string | Prior ETag; used when previous_sha256 is absent and response has ETag (quotes normalized). |
| previous_sha256 | string | Hex SHA-256 of last seen body. If omitted (and no previous_etag match), this call is a baseline (changed=null). |
| include_body_if_changed | boolean | If true and changed (or baseline), include truncated body text (~8KB) as body_preview. Default false. |
Output
Schema · Response
{
"type": "object",
"additionalProperties": true
}Tags
x402
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