Validate

Locate unparseable and out-of-range dates in CSV date columns

Scan date columns for invalid entries: impossible dates, ambiguous formats, and future or past-range anomalies.

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Why Onfyt: Detects calendar-impossible dates (Feb 30, Nov 31) separately from parse failures and range anomalies—three distinct error classes with separate severity.

Interactive Sample Data

id	name	dob
1	Grace Kerubo	1990-03-15
2	Peter Njoroge	1985-02-30
3	Mercy Akinyi	not provided

How this tool works

Date columns in CRMs, HR systems, and e-commerce databases frequently contain impossible values: Feb 30, month 13, or dates in the wrong format that parse to nonsensical values ('13/05/2024' becomes May 13 in MM/DD, but the intent was 13 May in DD/MM). Finding these before data analysis prevents silent statistical errors—averages over corrupted date ranges produce wrong tenure calculations, wrong customer lifetime values, and wrong cohort analyses. DataFix detects: dates that don't exist on any calendar, values that can't be parsed as dates at all, and dates outside an expected range (e.g., no customer date of birth should be in the future). Date columns frequently suffer from mixed formats (such as combining MM/DD/YYYY and DD/MM/YYYY), non-existent dates (like February 30), truncated timestamps, and textual placeholders ("Unknown", "TBD"). When loaded into time-series models or SQL databases, invalid dates abort transaction imports. DataFix parses date columns against strict calendar rules and standard datetime patterns, highlighting anomalous entries, invalid leap years, and out-of-range timestamps so you can normalize dates before ETL ingestion. Mixed date notations (such as MM/DD/YYYY versus DD/MM/YYYY) and nonexistent calendar dates (like leap year anomalies or month 13 entries) produce silent errors or parsing failures in time-series analysis. Auditing date columns against strict calendar rules ensures clean temporal consistency across records.

Things that usually go wrong

Ambiguous dates (01/02/2024) are flagged if both interpretations are plausible.
Future dates are not flagged unless you enable the 'no future dates' option.

Edge cases we tested

🧪 Feb 29 in a non-leap year

Flagged as invalid; leap year check applied correctly.

🧪 Date formatted as DD/MM/YYYY vs MM/DD/YYYY ambiguity

Ambiguous dates (01/02/2024) flagged with 'format ambiguous' warning.

🧪 Unix timestamp integer in date column

Detected and converted; treated as valid if timestamp within range.

Frequently Asked Questions

What makes a date invalid?

Dates that don't parse (e.g. '31/02/2024', 'Yesterday', '2024-13-01') and values that are obviously not dates.

Are time components validated?

Yes — '25:00:00' would be flagged as an invalid time.

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