Building reliable restock alerts is harder than a simple in-stock check

Developers building Restockd, a free app for tracking Pokemon and collectible restocks, found that real-time restock alerts involve far more complexity than a basic true/false inventory check. Retail product pages often display inaccurate availability, with cached data, regional differences, and checkout mismatches creating conflicting signals. The core challenge was determining when an observation was trustworthy enough to trigger a user notification, not just whether a page could be scraped. The team recommends separating raw inventory observations from alert decisions, and measuring false positives and late alerts as distinct failure types rather than lumping them together as bad data. They also highlight the need for alerts to have their own lifecycle, independent of the underlying stream of inventory events, to avoid bombarding users with duplicate or misleading notifications.