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Password-protect a PDF with AES-256

Set a password that is needed to open the file. Encryption uses AES-256 (qpdf, compiled to WebAssembly) on your device.

Tool · runs in this tab · free
Drop a PDF anywhere on this page

Or choose one. It is read in this tab, processed in a Web Worker, and never uploaded.

Read in this tab. Never uploaded.

How this runs

Nothing loads until you add a file. Then the engine starts in a Web Worker in this tab.

This jobwaiting
Requests since your file0
Other origins contacted0
Engineqpdf (WASM), Web Worker
Reported by this page. Check it yourself: switch off your network and run the tool again.

What the password does and doesn’t do

The open password encrypts the file’s contents with AES-256 (PDF 2.0 security handler, revision 6), which current versions of Acrobat, Preview, Chrome, Edge and Firefox can open. Without the password the content cannot be read.

Print, copy and edit restrictions are different: they are instructions that well-behaved viewers follow, not encryption. Treat them as a polite request.

Share the password by a different channel than the file (a phone call, a text), and choose a long one. If you lose it, nobody, including us, can open the file: we never see it.

Steps

  1. Add the PDF.
  2. Type a password (and an optional separate owner password).
  3. Choose print, copy and edit permissions.
  4. Encrypt and download.

Limits, stated plainly

  • Some government portals reject password-protected PDFs; send those unencrypted.
Already have Preview or Edge? Preview on a Mac can encrypt a PDF (File → Export, tick Encrypt).

Engine: qpdf (WebAssembly) in a Web Worker. Your file is not uploaded; check it yourself.