Guide
Anonymize a PDF.
A contract to have reviewed, a file to pass on, a ruling to publish, a document to hand to an AI: the PDF goes out, the names should not go with it. Anoni finds the personal data in the file, you check it, then you choose: remove it for good, or replace it and keep a way back. Everything happens on your computer.
Updated 3 November 2026
The method
Step 01
Drop the PDF on Anoni
The home screen asks “What would you like to anonymize?”. Drag the PDF in or pick it from disk: the analysis starts on its own. A scanned PDF is read by local text recognition.
What Anoni finds
- First and last names
- Addresses, phone numbers, e-mails
- IBANs, company and social security numbers
- Dates
Detection runs on your computer
Step 02
Check what Anoni found
Every piece of data found is highlighted. Click a highlighted word to keep it; click a plain word to add it. No automatic detection is perfect: this review is the step that matters.
Step 03
Cover what is not text
A signature, a stamp, a photo, a logo: the “Black zone” tool draws a rectangle by hand. It works on PDFs and images.
Step 04
Choose: reversible or for good
“How to share?” offers two choices. “Pseudonymize” is reversible: each piece of data becomes a token or a realistic name, and an encrypted vault keeps the mapping. “Redact” is irreversible: black bars, text removed.
Step 05
Save the new PDF
Save the redacted or pseudonymized PDF and pick where it goes. A redacted PDF is read back by Anoni after writing, before it shows as saved and checked. The original PDF is never modified.
What to know
Anonymize, redact, pseudonymize.
In everyday language, anonymizing a PDF means taking out what identifies someone. There are two ways to do it. Redaction removes the data: it no longer exists in the file, and nobody will get it back, you included. Pseudonymization replaces it with a stand-in and keeps the key to reverse it somewhere else. The choice comes down to one question: will you need the real data later?
When to redact.
When the document leaves for good and its recipient has no need to know who is in it: a published decision, a document disclosed to a third party, a training example, a public record. A redacted PDF has no text under the bars, and none of the original file's properties, such as author or title.
When to pseudonymize.
When you are still working on the document and will need the real data back: an outside review, an analysis handed to an AI, an ongoing case. Names become ⟦…⟧ tokens, or realistic names if the document has to read naturally. The vault links each token to its real value. It is encrypted, stays on your computer, and opens with a passphrase of at least eight characters.
What the GDPR says.
A pseudonymized document still holds personal data under the GDPR, since it can be reversed. A redacted one comes closer, but anonymity in the legal sense means nobody can be identified any more, even by combining what is left with other information: a rare job title, a date and a town are sometimes enough. Read what remains around the bars, not just the bars.
A scanned PDF.
A scan has no text, only images. Anoni reads it with local text recognition, then works as on any other PDF. When redacting, a page that no reading manages to decode is covered in full rather than left in the clear. Handwriting can slip past recognition: check the preview.
Nothing leaves your computer.
Anonymizing a PDF on a website means first sending it, personal data included, to the service that anonymizes it. Anoni reads, analyses and writes the file on your own machine. Once the app is installed, everything works offline. In the free version, exported PDFs, redacted or pseudonymized, carry an “anoni.dev” watermark, announced before saving; Anoni Pro removes it.
Questions
How do I anonymize a PDF for free?
With the free version of Anoni: detection, review, redaction and pseudonymization are all in it. Exported PDFs then carry an “anoni.dev” watermark. Anoni Pro removes it.
Is an anonymized PDF anonymous under the GDPR?
Pseudonymized, no: it can be reversed, so it is still personal data. Redacted, it can be, provided nothing else in the document lets someone find the person.
Can I get the original data back?
After pseudonymization, yes, with the vault and its passphrase. After redaction, no: the text is no longer in the file.
Do I need Adobe Acrobat?
No. Anoni reads the PDF and writes the new file itself. A black rectangle drawn in a PDF editor, on the other hand, often leaves the text underneath: it can be selected and copied.
Is the text still selectable?
Not in a redacted PDF: its pages are rebuilt as images, which is what guarantees there is nothing under the bars. If you need editable text, save a redacted Word document.
Which systems?
macOS, Windows and Linux.
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.
- 3 November 2026PDF or scan to Word: lawyers and notariesSubmissions, contracts, co-ownership rules, old deeds: bring them into Word without them leaving the firm.
- 3 November 2026Watermark a PDFOne sentence repeated on every page, baked into the image. Free, local, and it does not peel off.
To anonymize your PDF, download Anoni. See also how to redact a PDF, in detail, pseudonymization or anonymization, and the re-identification risk.