Free tool // 04 · Anonymizer
Data Anonymizer
Drop in a CSV and it flags emails, phone numbers, SSNs, credit cards, IPs, ZIP codes, and likely name and address columns. Pick what to mask, check the before/after preview, download the clean file. Nothing is uploaded — the whole thing runs in your browser.
Client-sideNo signupFile never leaves this tab
Run it on a file
CSV · 5 MB maxProcessing happens entirely on your machine. You could disconnect from the internet after this page loads and the tool would still work.
Share the shape of your data — not the people in it.
What it detects
8 pattern typesSix regex patterns scan every cell, and two column-name heuristics catch fields that hold names and addresses. Masking is one-way: values are replaced with fixed placeholders, so keep your original file.
| Pattern | What it matches | Masked as |
|---|---|---|
| Email addresses | Anything shaped like name@domain.tld, in any column | ***@***.*** |
| Phone numbers | US formats — dots, dashes, spaces, parentheses, optional +1 | ***-***-**** |
| SSN / tax IDs | Nine digits, with or without dashes | ***-**-**** |
| Credit card numbers | Sixteen digits — spaced, dashed, or run together | ****-****-****-**** |
| IP addresses | IPv4 dotted quads | ***.***.***.*** |
| ZIP codes | Five digits, ZIP+4 included | ***** |
| Name columns | Column headers like name, customer, contact, employee, patient | *** |
| Address columns | Column headers like address, street, city, state, zip | *** |
Questions
Straight answersDoes my file get uploaded anywhere?
No. Parsing and masking run in your browser with client-side JavaScript. The file never touches a server — there is no server side to this tool.
Can the masking be reversed?
No. Values are replaced with fixed placeholders, not encrypted, so the output contains nothing to recover. That also means the masking is destructive — keep your original file if you need the real values.
What files does it accept?
CSV, or a CSV-formatted .txt, up to 5 MB, with a header row. The detector reads the header names to spot name and address columns, so files without headers will only get pattern-based masking.
Does this make my data GDPR-compliant?
It helps, but treat it as a first pass, not a guarantee. Detection is pattern-based, so unusual formats and free-text fields can slip through. Review the preview before you share anything.
Masking one file is easy. If PII needs handling across a whole pipeline — exports, backups, warehouse tables — that's a service we run, and the first audit is free.