CSV & Excel column mapper
Map CSV or XLSX columns to your own schema, validate each row and export safe text-preserving workbooks.
LOCAL DATA WORKSPACE
Choose the fields. Keep control of every row.
Your file stays in this browser. No upload, account or AI is needed.
Up to 5 MiB, 5,000 data rows, 100 columns and 100,000 cells. XLSX: values only; no formulas, macros, external links or encrypted workbooks.
How it works
- Choose a CSV, TSV or values-only XLSX file and confirm the worksheet and header record.
- Choose source columns, target names, types and required fields. Keep identifiers as text.
- Review row errors and download validated data as CSV, text-cell XLSX or a complete JSON report.
Example & practical use
Map supplier columns to your required fields while preserving identifiers such as 000123 and flagging invalid dates or prices.
Limits and help
Local processing, up to 5 MiB, 5,000 rows, 100 columns and 100,000 cells. Formulas, macros and external workbook links are rejected. Only cell values are imported. CSV formula protection adds apostrophes; use XLSX to preserve identifiers when opening in Excel. No remote import or automatic data repair.
Your files are yours.
Image and text processing happens in your browser. Your files are not uploaded to our servers.
Troubleshooting
Try the small example on this page first. If it works, check your input format and size limit. Save any needed input before reloading. You do not need to share a file or password to report an issue.