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Stall-Row URL Change Detection Recheck
x402
Stall-Row URL Change Detection Recheck is a paid API for AI agents from stall-row-production.up.railway.app, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-29).
Probes a monitored URL (x402 resource or web page) without paying it and returns BASELINE, UNCHANGED, or CHANGED with a field-by-field diff against the last recorded state.
Price / call$0.005
Success—
StatusUnknown
How this service works
Change detection for anything with a URL, built for monitoring loops: probe one x402 resource or web page WITHOUT paying it and answer BASELINE, UNCHANGED, or CHANGED with a field-by-field diff (price, asset, payTo, schema, page body) against the last check for that watch. Use this when an agent runs on a schedule and needs to know what changed before spending money or attention. Watch and pack state persist across redeploys on the service volume. Packs: $1 for 250 checks on one endpoint.
Output
Returns a status of BASELINE (first check, establishes initial snapshot), UNCHANGED (no differences detected), or CHANGED (differences found), along with a field-by-field diff covering price, asset, payTo, schema, and page body changes compared to the last stored state for that watch ID.
Example use cases
Price alert before spending crypto
“Before I pay for that x402 data feed at https://feeds.example.com/prices, recheck watch 'watch_feed01' with pack 'pack_main' and tell me if the price or payTo address has changed since yesterday.”
Scheduled content monitoring loop
“Run the recheck for watch ID 'watch_blog42' using pack 'pack_daily' against https://news.example.com/latest — has the page body changed since the last time we checked?”
Agent guard before downstream action
“Before my agent triggers the next workflow step, use watch 'watch_guard01' and pack 'pack_ops' to recheck https://api.partner.com/config — if anything in the schema or asset fields has changed, stop and tell me what's different.”
Technical details
Endpoint
POSThttps://stall-row-production.up.railway.app/v1/recheck?utm_source=zero.xyzWhen to prefer
Choose this endpoint when running scheduled agent loops that need to detect changes on x402 resources or web pages before spending money or attention on them. It is ideal when you want a cheap, stateful diff ($0.004–$0.005 per check) against a persisted baseline rather than fetching and comparing content yourself. Prefer it over generic web scrapers when you specifically need price, payTo, asset, or schema-level diffs on x402-compatible resources.
Side effects
- Invalid or unreachable URL returns an error with no status
- Unknown watch_id may fail to find prior state, falling back to BASELINE
- Expired or exhausted pack_id returns a payment-required or quota-exceeded error
- Malformed input schema returns a 400-level validation error
- Target URL returning non-standard responses may produce incomplete diffs
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | |
| pack_id | string | |
| watch_id | string |
Tags
x402
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