Data anonymizer — mask PII columns in a CSV
Paste a CSV, name the columns that hold personal data, and get a copy with those columns masked, hashed or redacted — ready to share safely. It runs entirely in your browser (0 uploads, works offline).
How to use it
- Paste your CSV (the header row names the columns).
- List the columns to mask and choose a method — mask, hash or redact.
- Copy or Download the anonymised CSV.
FAQ
How do I anonymise a CSV before sharing it, for free?
Paste the CSV, list the sensitive columns (for example name,email,phone) and pick a method. This page rewrites just those columns and leaves the rest intact — on your device with no upload, which is the only safe way to anonymise real data.
What is the difference between mask, hash and redact?
Mask keeps the first and last character and hides the middle. Hash replaces the value with a stable pseudonym, so equal values still match across rows but the original is not recoverable. Redact blocks the value out entirely.
Is my data uploaded anywhere?
No. Anonymisation runs entirely in your browser and nothing is transmitted or stored, which you can verify by turning off your Wi-Fi. Uploading data to anonymise it would defeat the purpose.
Does hashing let me still join tables?
Yes — hashing is deterministic within a document, so the same input produces the same pseudonym, which preserves joins while removing the real value.
Limits
Masks the columns you name; it cannot detect sensitive values hiding in free-text columns you did not select.
Related
The PII detector finds personal data first; the mock data generator invents fake data instead.
Bookmark this page (Ctrl+D, or ⌘D on Mac) or install the app — it works offline the next time you need it.