Historical Stock CSV Quality: Dates, OHLC Ranges & Gaps

Inspect a daily single-series price file before using it in screening, charting or a simulation.

Map one series deliberately

The canonical columns are date,open,high,low,close,volume,adjustedClose. Dates are daily YYYY-MM-DD labels; prices are positive plain decimals. This inspector is not an intraday timestamp converter, multi-symbol deduplicator or parser for macroeconomic rates.

Check structural constraints

High must cover open, low and close; low must not exceed open or close. Repeated dates are blocking findings: identical duplicate rows are not automatically safe to keep, and conflicting duplicates need source review. Descending input is retained and warned about rather than silently sorted.

Interpret the calendar warning

Weekday mode excludes Saturdays and Sundays only. It does not know exchange holidays, exceptional closures, suspensions, listing dates or timezone-specific sessions. Calendar mode expects every date; no-calendar mode disables that test. A missing-date list is a prompt to investigate, not proof of missing trades.

Keep the original before a repair

The local inspector retains all raw strings and exports a full JSON backup, source CSV and findings. Sorted CSV is enabled only with zero blocking errors, but warnings can remain. It never inserts bars, chooses a duplicate, corrects a split or certifies a complete feed.