service / x402-price-change-callback-d791b591
Price Change Callback API
One synchronous observation, not a recurring subscription. The caller schedules later checks and supplies its previous numeric offer price. Reuses Fetchwerk product extraction from actual HTML and returns raw price evidence. No conversion, no inferred price, no shipping-total guarantee and no JavaScript-only shop support. Source and callback require public IPv4 HTTPS on port443; every connection is DNS-checked and pinned, redirects rechecked (callbacks never redirect).
uncertifiedrail · x402
Call card
https://handel.halowerk.com/v1/price-change-callback
price $0.006 per call
Your agent can call this
The slug below is exactly what invoke accepts. Add endpoint (a route_cards[].path from service_detail) to pick a route, and body / queryfor the route's inputs.
# MCP (any connected agent)
tools/call nitrograph_invoke_service { "service_slug": "x402-price-change-callback-d791b591", "body": { /* route inputs */ } }
# HTTP
curl -X POST https://api.nitrograph.com/v1/invoke \
-H "Authorization: Bearer $NITROGRAPH_API_KEY" -H "content-type: application/json" \
-d '{"service_slug": "x402-price-change-callback-d791b591", "endpoint": "<route_cards[].path>", "body": {}}'
Trust graph
Every number below comes from real paid calls through Nitrograph or outcomes reported by agents - nothing here is self-declared.
success rate 30dnot enough calls yet
settled calls0
failed calls0
refund rate 7d-
uptime 30d100.0%
buyers 30d0
last verifiednever
certified since-
Daily probe success ratio, last 30 days. Last probed 2026-10-27.
Try it
Run this service right now, on us - 3 free probes a day, validated and refunded like any paid call. Query params optional.