Anonymize spreadsheets without uploading them
Drop an Excel or CSV file, choose how each column is anonymized, and download the result. Everything runs on your computer, in this browser tab.
Your data never leaves your browser
Anonymizer
1. Columns
Suggestions come from column names and a sample of values. Check them before you anonymize: detection helps, but you decide.
| Column | Detected | Treat as | Method | Options |
|---|
Presets (optional)
Save these column settings under a name, like “CRM export”, and apply them to the next file with the same column names.
2. Consistency
With the same project secret, a value is always replaced by the same fake or hash, so anonymized files can still be joined. Anyone with the secret and the original data could reproduce the mapping, so keep it private.
New secret generated. Copy it somewhere safe now: it is not stored anywhere unless you tick the box below, and it cannot be recovered.
3. Preview (first 20 rows)
4. Anonymize
The mapping file undoes the anonymization. Anyone who has it can see the original values. Store it somewhere secure, and never send it along with the anonymized file.
The download contains the selected sheet only, with values (not formulas or formatting).
Download the mapping file Keep it secure and separate from the anonymized file.
How it works
- Open a file. It is read by this page with JavaScript. No upload, no account.
- Review each column. Scrubsheet suggests what the column contains (emails, phone numbers, names, IBANs, national IDs from 18 countries…) and how to treat it.
- Download. The anonymized copy is built in your browser and saved to your computer.
Methods
- Fake
- Realistic replacement in the same format. Fake IBANs, card numbers and ID numbers pass their checksums.
- Redact
- Replace with
[REDACTED]or your own text. - Mask
- Hide all but a few characters, like
************1234. - Hash
- Keyed HMAC-SHA256, shortened. Same input and secret, same hash.
- Generalize
- Dates to year or month, numbers to ranges, postal codes to a prefix.
- Shuffle
- Mix values between rows within the column.
- Clear / Keep
- Empty the column, or leave it untouched.
Your data never leaves your browser
This is not a promise in a policy: the page is built so that it cannot send your data anywhere.
-
No network access. A strict Content-Security-Policy (
connect-src 'none') makes the browser block every request the page or its worker might try to make, including to our own servers. - No backend. The tool is a set of static files. There is nothing to upload to.
- No analytics, no cookies, no trackers.
- Tested. An automated test runs every detector and method with all network APIs replaced by tripwires, and fails if any of them is touched.
- Check it yourself. Open your browser's developer tools, go to the Network tab and anonymize a file. Or load the page, disconnect from the internet, and use it offline.
FAQ
Is it really free?
Yes. The browser tool is free, with no row limits or sign-up.
How large can a file be?
Hundreds of thousands of rows work fine. Processing runs in a background worker, so the page stays responsive. The practical limit is your computer's memory.
Is anonymized data still personal data?
It depends. Replacing direct identifiers is pseudonymization; other columns (a rare job title, a small town, a precise date) can still identify people when combined. Review the result, and generalize or clear columns you don't need.
Could a fake ID number belong to a real person?
For Finland and Norway, fakes use the ranges reserved for test data. For other countries no reserved range exists, so a checksum-valid fake could coincide with a real number. It is not linked to your original data, but if that matters, use Mask, Hash or Redact.
What does deterministic mode do?
With a project secret, the same value always gets the same replacement, in every file and every session. That keeps anonymized files joinable. Without a secret, each run uses a fresh random key that is thrown away afterwards.
Are formulas and formatting kept?
The download contains cell values of the selected sheet. To anonymize inside a workbook while keeping everything else, use the Excel add-in.
Working in Excel?
The Scrubsheet add-in brings the same anonymization into Excel on Windows, Mac and the web. It writes to a new worksheet, so your original stays untouched.
Support this tool
Scrubsheet for the browser is free. If it saved you time, you can leave a tip.