About this tool
CSV Data Anonymizer is a free, in-browser tool that turns a CSV containing personal data into a demo-safe version you can share. It parses your file, auto-detects likely PII in each column — emails, phone numbers, IP addresses, credit-card-like numbers and SSN-like patterns — and suggests masking. For every column you choose an action: keep it as-is, redact to ****, hash with SHA-256, replace with realistic fake values, or drop the column entirely.
All processing happens locally in your browser using JavaScript and the built-in Web Crypto API for hashing; your data is never uploaded, never stored and never leaves your device, which is what makes this safe for real customer exports. The output CSV updates live as you change any column's action, and you can copy it or download it directly.
Frequently asked questions
Which column actions are available?
Keep leaves values untouched; Redact replaces every non-empty value with ****; Hash replaces each value with a deterministic SHA-256 digest (first 16 hex characters) so equal inputs map to equal hashes; Fake substitutes realistic same-shaped values based on the detected type; Drop removes the column from the output.
How is PII detected, and is detection reliable?
Each column is sampled and matched against regular expressions for emails, IPs, SSN and phone/card number shapes; a type is suggested only when at least half the sampled values match. Detection is a heuristic starting point — always review the suggested actions before sharing the result.
Is my data uploaded or stored anywhere?
No. Parsing, detection and SHA-256 hashing all run entirely in your browser with the Web Crypto API, so no data is sent to a server and nothing persists after you close the tab.
What CSV conventions are assumed?
Fields use the selected delimiter (comma, semicolon, tab or pipe), double quotes wrap fields containing the delimiter or newlines, and a literal quote is doubled. When 'first row is a header' is on, that row's names are shown next to each column and are passed through untouched.
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