CSV Date Column Fixer
Fix Excel serial numbers and date formats in one selected CSV column.
Choose one date column. Every other column stays unchanged.
Your data is processed locally in your browser whenever supported and is not uploaded to our servers.
Keep working
Related tools
CSV ↔ JSON Converter
Convert CSV to JSON or JSON objects to CSV locally with validation and spreadsheet-safe output.
Open tool →CSV Splitter
Split CSV files by size or row count. Keep related rows together, repeat headers and download every part as a ZIP — privately in your browser.
Open tool →Google Calendar CSV Import Prep
Validate calendar rows and download a Google Calendar-ready CSV without guessing dates.
Open tool →