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ChgWatch Diff — Web Page Change Detector
x402
ChgWatch Diff — Web Page Change Detector is a paid API for AI agents from api.firstmention.uk, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-29).
Checks one or more URLs for content changes since a stored or hashed baseline, returning a diff summary with added/removed line counts and a current hash.
Price / call$0.01
Success—
StatusUnknown
How this service works
Pay-per-call HTTP APIs, paid with x402 in USDC on Base (eip155:8453): agentkit, api-change-check, basedue, basewatch, chainread, check-sanctions, chgwatch, company-facts, composite, edgar, feednews, pageaudit, solcheck, token-dd, txpreflight, walletcheck, webmd, webread, websearch, x402index. Each operation describes its service.
Output
Returns a JSON object with an overall ok flag, total count of URLs checked, a results array per URL containing ok status, changed boolean, added_count and removed_count of lines, and current_hash; plus top-level any_changed, error_count, changed_count, and need_baseline_count aggregates.
Example use cases
Competitor pricing page monitor
“Check if https://competitor.com/pricing has changed since its stored baseline — use text mode so I can see what lines were added or removed.”
Regulatory page change alert
“Has https://sec.gov/rules/final.htm changed since the hash abc123def456? Show me the diff in markdown mode with 10 lines of context.”
Batch content freshness check
“Check all three of these pages for updates against their stored baselines: https://blog.example.com/post1, https://blog.example.com/post2, https://blog.example.com/post3 — tell me which ones changed and how many lines were added or removed.”
Technical details
Endpoint
GEThttps://api.firstmention.uk/s/chgwatch/diff?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need to detect content changes on one or more specific URLs with diff-level granularity (added/removed line counts and hash comparison) rather than just a reachability ping. It is ideal for monitoring competitor pages, regulatory filings, documentation sites, or any scenario where the agent needs to act only when content actually changes. Prefer it over generic web scrapers when change detection — not content extraction — is the primary goal.
Side effects
- URL is unreachable or returns non-200 — ok:false for that result, increments error_count
- No stored baseline exists for a URL in stored mode — increments need_baseline_count, changed is indeterminate
- More than 20 URLs submitted — request rejected
- Invalid mode enum value — schema validation error
- Payment not provided or insufficient — 402 Payment Required response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"checked": 2,
"results": [
{
"ok": true,
"url": "https://example.com/",
"changed": true,
"added_count": 2,
"current_hash": "0a080719be9f",
"removed_count": 1
}
],
"any_changed": true,
"error_count": 0,
"changed_count": 1,
"need_baseline_count": 0
}
}Tags
x402
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