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CSV Anonymizer

A CSV anonymizer replaces personal spreadsheet columns, such as names, emails, phone numbers, and IP addresses, with consistent fake values, so duplicate records and joins still match, while columns like city or order total are left untouched by default.

Spreadsheet

Drop a spreadsheet here or click to browse

or paste rows from a spreadsheet (⌘V)

CSV, TSV, TXT, XLSX

Files stay in your browser. Nothing is uploaded.

How to anonymize a CSV or Excel file

  1. Add your spreadsheet

    Drop a CSV, TSV, TXT, or Excel file, or paste rows copied from a spreadsheet.

  2. Review the detected columns

    Columns that look like names, emails, phone numbers, or other personal data are flagged automatically.

  3. Choose an action per column

    Pick Keep, Fake, Mask, Black out, or Remove for each column from its header dropdown.

  4. Download the anonymized file

    Download the result as a CSV with the personal data replaced throughout.

Why use this tool

Automatic column detection

Column headers and a sample of each column's content are checked together to flag names, emails, phone numbers, addresses, dates of birth, ID numbers, IP addresses, and financial details.

Consistent fake values

The same person's name, email, phone number, or IP address maps to the same fake value everywhere it appears, so duplicate rows and repeat records still match after anonymizing.

Five actions per column

Keep a column as is, replace it with a realistic fake value, mask most of each value, black it out completely, or remove the column outright.

Handles large files

Spreadsheets with tens of thousands of rows stay responsive. Only a preview is computed live; the full file is built when you download.

Nothing leaves your browser

Spreadsheets are read and anonymized locally. Files are never uploaded.

About this tool

A CSV anonymizer checks every column in a spreadsheet against its header name and a sample of its own values, then flags the ones that look personal, such as names, emails, phone numbers, postal addresses, dates of birth, ID numbers, IP addresses, and financial account details. Columns like city, order total, or product ID are left alone by default.

Each flagged column defaults to a realistic fake replacement: a name becomes something like Person 17, an email becomes user17@example.com, and so on, with the same original value always mapping to the same fake one, even across different columns of the same kind. That keeps duplicate customers and matching records usable after anonymizing. Any column's action can be changed from its header: keep the original value, mask most of it, black it out completely, or remove the column. CSV to JSON and JSON to CSV handle format conversion if the anonymized file needs to move between a spreadsheet and code.

CSV, TSV, and plain text files are read with their original delimiter preserved in the download. Excel workbooks are read sheet by sheet, with dates converted to a plain date format and numbers turned into text. Rows copied directly from a spreadsheet can also be pasted in rather than saved to a file first. For projects that need made-up data from scratch rather than anonymized real data, see the mock data generator.

Frequently asked questions

Does the spreadsheet ever leave my computer?
No. The file is read and anonymized in your browser; nothing is uploaded to a server.
How are personal columns detected?
Each column's header and a sample of its values are checked together. A column counts as detected when most of its sampled values match a known pattern, such as an email address or an IP address, or when its header matches a common name for that kind of data, like "phone" or "dob".
What file types are supported?
CSV, TSV, and plain text delimited files, plus Excel .xlsx workbooks. Rows copied from a spreadsheet can also be pasted in directly.
Will the same person get the same fake value everywhere?
Yes. A name, email, phone number, or similar value is replaced with the same fake value every time it appears, including across different columns of the same kind, so duplicate rows and repeat records stay consistent.
Is there a limit on file size?
Spreadsheets with tens of thousands of rows stay responsive. Only a short preview is shown while editing; the full file is built when you download or copy.

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