Spreadsheet Data Masking

Mask emails, phone numbers, card numbers and SSNs across every cell in a CSV.

Redaction & masking Client-side SheetJS from CDN + rules

Tool preview

How to use it

! Masking is detection-based; a column of plain names is not anonymised.
! It keeps the CSV structure but rewrites values in place, so the original file is not recoverable from the output.

Does it mask whole columns?

It masks detected values wherever they appear, not whole columns.

Can I keep the last four digits?

Yes, the partial masking mode keeps a short prefix and suffix.

Is the table uploaded?

No.

Processing happens in your browser using the File API, WebAssembly and Web Workers. There is no upload endpoint.

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