Stock API Charts Need Complete Downloads and Explicit Data Gaps

Summary: A stock chart can look convincing even when its history is incomplete. A stock API supplies records under specific retrieval and aggregation rules; your application must finish the download and preserve missing observations. This article explains pagination, absent candles, and a small Python example that keeps an unknown price from becoming a false market move.

A stock API is a programmatic interface for retrieving stock-related data. For a historical chart, that often means requesting bars: records containing open, high, low, close, and volume for an interval. Those records can power chart viewers, research dashboards, and historical comparisons. They do not, by themselves, establish that every part of your requested window has been downloaded.

Consider a chart that has prices before and after a missing minute. Replacing the missing price with zero invents a collapse.…