The Silent Failure: Why Scrapers Collect Only Half the Data

Web scrapers can silently collect incomplete datasets while passing all standard checks—HTTP 200 responses, valid row schemas, and byte confirmations all pass. The culprit is often pagination systems that repeat earlier pages or cap results, causing duplicates to hide the missing data behind large-looking row counts. Completeness checks comparing collected unique IDs against declared totals are essential, as they operate at a different layer than correctness or status checks.