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Mask Private Data in Excel / CSV
Mask, redact, or replace one selected column with per-run pseudonyms without uploading the file.
Drop files here or choose files from your device
Processing happens directly on your device. No file bytes are uploaded, and this tool uses no Cloudflare Container compute.
How to use Mask Private Data in Excel / CSV in 3 steps
- Choose your file: Supports .xlsx, .csv, .tsv; Maximum 15 MiB; XLSX 2 MiB
- Review the preview or confirm processing: Processing happens directly on your device. No file bytes are uploaded, and this tool uses no Cloudflare Container compute.
- Get the result immediately: Download the processed file and open it in Microsoft Excel or Google Sheets
Why does this problem happen, and how does this tool fix it?
Files shared with test teams or outside parties may expose citizen IDs, phone numbers, email addresses, or account numbers. Manual cell-by-cell editing is easy to miss and hard to review.
How it works and protects your data: Processing stays in your browser. Pseudonym mode uses HMAC-SHA-256 with a new non-extractable key for each run and stores no key. The output can remain personal or pseudonymous data and is not automatically anonymous or PDPA-compliant.
Frequently asked questions
Does masking one direct identifier make the file anonymous?
Not necessarily. Names, addresses, dates of birth, job details, or combinations of other columns may still identify someone. Review the entire dataset before sharing.
Will the same pseudonym be produced in a later run?
No. Equal values share a token only within one processing run. A fresh secret key intentionally produces different tokens in later runs.