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Protect PDF

Add a password to a PDF with strong AES-256 encryption. Everything runs in your browser — your file and password never leave your device.

How to password-protect a PDF

  1. Choose the PDF you want to protect.
  2. Type a password (twice, to avoid typos).
  3. Press Protect PDF — the encrypted copy downloads automatically.

Is it private?

Yes. The file is encrypted on your device with WebAssembly (qpdf) using AES-256. Nothing is uploaded — and if you lose the password, no one (including us) can recover the file.

Is it private?

Yes. Everything runs inside your web browser, using your own device. Nothing is uploaded to any server, so your documents stay completely private. On top of that, the tool runs in a private frame, served from a separate address (app.robinpdf.com) and kept apart from the ads: your browser does not let the page around it see the file you open there. How does this work without uploading?

Frequently asked questions

How strong is the encryption?

AES-256, the standard used for sensitive documents. The PDF cannot be opened without the password.

Is my file uploaded?

No. The encryption happens entirely in your browser, so your file and password never leave your device.