Runs in your browser. File never uploaded

Anonymize an Excel file (.xlsx) in your browser

Drop your Excel workbook, choose which columns contain PII, and download both the anonymized .xlsx and the mapping dictionary. Reversible if you want; one-way if you don't.

Drop a file to anonymize

CSV, TSV, TXT or Excel. Runs in your browser, never uploaded.

Supported: .csv, .tsv, .txt, .xlsx, .xls

Why Excel data needs anonymization

Excel workbooks travel by email, get shared on Teams or Drive, and end up on contractor laptops. Most of them carry PII. Customer emails, employee salaries, supplier IBANs. Anonymizing the sensitive columns before sharing reduces blast radius without losing analytical value.

Mask emails, names, phone numbers, DNIs, NIEs, IBANs and credit card columns
Preserve numeric columns (amounts, dates, quantities) untouched for analysis
Output stays as a real .xlsx. Opens in Excel, Sheets, LibreOffice unchanged
Reversible with the mapping file when you need the originals back

How to anonymize an Excel file

1
Drop the .xlsx
First sheet is parsed automatically. Multi-sheet workbooks: anonymize one sheet at a time.
2
Confirm detected PII columns
The detector pre-suggests methods for emails, names, phones and IDs. Override per column if needed.
3
Run preview, then full
100-row preview is free. Run the full anonymization (free under 2k rows) and download the .xlsx output plus mapping.

What stays, what changes

Numeric and date columns pass through untouched. Your pivot tables and SUMIFS keep working. Only the columns you explicitly anonymize are changed. The output workbook keeps the same column order and the same row count.

Header row is preserved. If you anonymize a column called 'email', the output still has 'email' as the header. Only the values change. This matters if your downstream tools expect a specific schema.

Restore originals when you need them

Keep the mapping file. To restore, drop both into the reverse tool and the original Excel comes back.

Open the reverse tool →

Frequently asked questions

Does it work with multi-sheet workbooks?+

Currently the engine reads the first sheet. For multi-sheet workbooks, anonymize each sheet separately and recombine in Excel.

Will the output still open in Excel?+

Yes. The output is a real .xlsx written with the same library Excel uses. It opens in Excel, Google Sheets and LibreOffice without issues.

What if my Excel has formulas?+

Formulas are read as their computed values at parse time. The anonymized output will contain the computed values (not the formulas).

Can I anonymize an .xls (old format)?+

Yes, .xls and .xlsm are accepted alongside .xlsx. The output is always .xlsx.