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fetchwerk Diff — Content Change Detection
x402
fetchwerk Diff — Content Change Detection is a paid API for AI agents from fetch.halowerk.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-14).
Compares a web page against its last stored snapshot, or two supplied documents, and returns only the content that has changed.
Price / call$0.003
Success—
StatusUnknown
How this service works
Compare a page against its last stored state, or two supplied documents, and report only the content changes.
Output
A structured diff report highlighting only the content that changed between two document versions — removed text, added text, and modified sections — along with optional echoed timestamps for provenance tracking.
Example use cases
Track competitor pricing page updates
“Check https://acmecorp.com/pricing against its last stored snapshot and tell me exactly what content changed — I want to know if they've updated their plan tiers or prices.”
Verify article edits between two drafts
“Here are two versions of our blog post — the before version is the original HTML and the after version is the revised draft. Can you diff them and show me only what's changed?”
Monitor regulatory page for new rules
“I need to know if https://sec.gov/rules/final.htm has changed since January 1st 2025 — pull the snapshot from that date and compare it to the current version, then report only the new or removed content.”
Technical details
Endpoint
POSThttps://fetch.halowerk.com/diffWhen to prefer
Choose this endpoint when you need to detect what specifically changed on a page or between two documents — not just whether a change occurred. It is ideal for monitoring tasks (pricing pages, regulatory filings, news articles) where you want a precise delta rather than a full re-extraction. If you have two documents in hand and want an offline comparison without any network access, supply before and after directly. Prefer a full-extraction sibling endpoint if you need the complete current content rather than just the delta.
Side effects
- URL not yet stored in the system (no prior snapshot available to compare against)
- Invalid or unreachable URL returns a fetch error
- Malformed HTML or Markdown in before/after fields causes parsing failure
- 'since' timestamp predates any stored snapshot, returning no baseline
- Both url and before/after fields omitted, leaving the comparison target ambiguous
- Rate limiting or payment failure (x402 protocol) blocks the call
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | Page to fetch and compare against its last stored state. |
| after | string | Later document as HTML or Markdown. |
| since | string | ISO timestamp. Picks the stored state at or before this moment instead of the newest one. |
| before | string | Earlier document as HTML or Markdown. No network access is used. |
| after_fetched_at | string | Optional, echoed back for inline comparisons. |
| before_fetched_at | string | Optional, echoed back for inline comparisons. |
Tags
x402
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