Guide
Choosing anonymization software.
Every tool promises to hide personal data. What sets them apart shows in seven questions, which you can ask any of them, Anoni included.
Updated 29 October 2026
Where do the files go?
This is the first question, because it decides the others. An online service receives your documents on its servers to anonymize them: that is already a transfer of personal data, with a contract, a retention period, sometimes a third country. Local software processes the file on your computer. Ask where the detection runs, not only where the results are stored.
What does it detect, in French?
Many tools are built for English. A French social security number, a SIRET, an address such as « 12 bis rue des Lilas », a name after « Maître » or « Madame » need rules made for French. Ask for the list of categories it detects, and for results measured on French documents.
Does it read your formats?
PDFs with text, scanned PDFs, Word, Excel, images, emails, data files. A tool that cannot read scans lets a good share of real documents through: letters received, signed deeds, older records.
Reversible or permanent?
These are two needs. To send a document to an AI and read its answer, you need pseudonyms you can decode. To publish or hand over a document, you need permanent redaction. A good tool does both, and says clearly which one it applies.
Does it really remove?
A redaction that leaves the text under the bar, or the author's name in the file properties, is not one. Test it: redact a PDF, try to copy its text, then open its properties.
Does it say what it did not do?
An honest tool re-reads what it produces and points out its limits: an unreadable page, a model that did not run, clues that still let someone be recognised. Be wary of « 100% anonymized » with no detail.
How much, and for whom?
Price per seat or per document, page limits, a licence for a whole firm. Look at what has to be installed, too: a local app needs installing, an online service does not. That is the real price of confidentiality.
Where Anoni fits.
Anoni is local software for macOS, Windows and Linux. It detects personal data in French documents: PDFs, scans, Word, Excel, images, emails, and data files (CSV, SQLite, SQL dumps). It redacts or pseudonymizes with an encrypted vault, re-reads the files it writes and points out the re-identification risk. It has a free version and a Pro version. It does not make a document anonymous for you: it reduces what leaves, and it tells you what it did not do.
Frequently asked
Is free software enough?
For many documents, yes. Anoni's free version covers the whole flow. Pro removes, among other things, the « anoni.dev » watermark on redacted PDFs and the 1,000-row limit per table.
Can you just ask an AI to anonymize?
Not without first sending it the data you want to protect. That is the whole problem: anonymization has to happen before anything is sent.
Can an online tool be GDPR-compliant?
Yes, with a processing agreement and safeguards. But every document goes through it first. A local tool removes that step.
The numbers are in the benchmark and the comparison. See also local vs cloud, can an AI anonymize a document and the other guides.
More guides
- 14 October 2026Convert a PDF to WordA PDF into an editable .docx, on your own machine. What the conversion keeps, and what it does not.
- 27 September 2026Watermark a PDFOne sentence repeated on every page, baked into the image. Free, local, and it does not peel off.
- 29 October 2026Protect your rental applicationYour documents go out to strangers, several times over. A watermark says what they are for, and what they are not for.