Guides

Anonymize or pseudonymize data in Excel

Excel has no built-in way to anonymize a sheet. The usual workarounds, RAND() columns, find and replace, deleting columns by hand, are slow and easy to get wrong in free-text cells. A detour through CSV does the job in a few minutes, without the sheet leaving your computer.

Step by step

1. Save a copy as CSV: File, Save As, "CSV UTF-8 (Comma delimited)". Only the active sheet is saved, without formulas or formatting, so keep the original workbook.
2. Open the anonymizer with the Table (CSV) preset and choose Open file. The file is read by your browser, not uploaded; files up to 5 MB fit.
3. Tick the columns to replace entirely: names, emails, phone numbers, customer numbers. Every row below the header is replaced, whatever the values look like.
4. Review the findings in the other columns, especially notes and comments.
5. Download the result and open it in Excel. If special characters look wrong, use Data, From Text/CSV and choose UTF-8.

Anonymize or pseudonymize?

• Fake data, the preset's default, gives realistic values for test data and demos; the originals are not kept.
• Hashes pseudonymize: the same customer gets the same code in every row, so pivot tables, counts and lookups across sheets still work.
• Placeholders pseudonymize reversibly: export the mapping file if you need to put the original values back later, and keep it as safe as the original data.

What is left in the sheet can still point to a person: a rare job title with a postcode and a birth year. Drop the columns the purpose doesn't need. More on the terms in pseudonymization vs. anonymization.