Guide
Blur a PDF.
You blur a name, a number or a face so nobody can read it. In a PDF that is often an illusion: the blur can be read, and the original text sometimes stays under the blurred image. Anoni does not blur. It does better: it removes the data from the file and puts a black bar in its place, 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 and the analysis starts on its own. Names, addresses, numbers and e-mails are highlighted.
Step 02
Choose what has to go
What you meant to blur is often highlighted already. Click a highlighted word to keep it, a plain word to add it.
Step 03
Cover faces, signatures and stamps
The “Black zone” tool draws a rectangle over what is not text: an ID photo, a face, a signature, a stamp. It works on PDFs and images.
Step 04
Choose “Redact” and save
Under “How to share?”, “Redact” is the irreversible choice: black bars, text removed. Save the redacted PDF, and Anoni reads the written file back before showing it as checked.
What to know
Blurring does not always remove.
Most tools blur by laying a blurred image over the page. The original text stays in the file, under the image: it can be selected, copied, found with a search. It is the same mistake as a black rectangle drawn in a PDF editor, only less visible.
A blur can sometimes be read.
A light blur over printed text lets the letters show through, especially when you know what you are looking for: a number format, a short name. Pixelation is no safer: public tools can reconstruct pixelated text. The shorter and more predictable the data, the weaker the blur.
What Anoni does instead.
It redacts. Each page is redrawn as an image, the bars are painted on it, and a new PDF is written from those images. The original text is not copied into it, and neither are file properties such as author or title. There is nothing under the bar, and nothing to unblur.
When a blur is enough.
To illustrate a screenshot with nothing sensitive in it, or to soften a background, a blur does the job. As soon as it is personal data, an account number or a face that must not be recognized, remove it rather than scramble it.
Nothing leaves your computer.
Blurring a PDF on a website means first sending it, along with what you wanted to hide. Anoni works on your own machine, offline once installed. In the free version, the redacted PDF carries an “anoni.dev” watermark, which Anoni Pro removes.
Questions
Can Anoni blur a face?
No, it covers it. The “Black zone” tool draws an opaque rectangle over a face, a photo or a signature, and the area is removed from the file, not scrambled.
Is a blurred PDF anonymized?
Not necessarily. If the text stays under the blur, or the blur can be read, the data is still there. Redaction that takes it out of the file is the safe way to remove it.
Can I blur a PDF online?
Yes, plenty of websites offer it, but you have to send them the whole document, data included. Anoni does the work on your computer.
What about an image or a screenshot?
Anoni takes images too. “Black zone” works on them as on a PDF, and the result is saved as a redacted image.
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 hide part of your PDF for good, download Anoni. See also how to redact a PDF, in detail, and how to anonymize a PDF.