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How to password-protect a PDF

Contracts, payslips, medical results: some PDFs should not open for whoever finds them in an inbox. PDF has encryption built in, and you do not need Acrobat to use it.

Add a password

  1. Open Protect PDF and type the password the reader will need. Optionally set a different owner password that allows editing and permission changes.
  2. Drop one or more PDFs.
  3. Download. The files are encrypted with AES-256, the strongest scheme the PDF standard supports.
Password-protect a PDFEncrypt a PDF with a password in your browser using AES-256. Optional separate owner password. Files never leave your device.

Send the password separately — a text message, not the same email. Encryption is only as good as the password, so use a long one; a passphrase of four random words beats Pa$$w0rd by a wide margin.

Remove a password

Typing the password every time gets old. Unlock PDF makes an unprotected copy of a file whose password you know. It also removes owner restrictions (no printing, no copying) — leave the password field empty for those.

Remove password from PDFRemove the password from a PDF you own, in your browser. Enter the password once and download an unprotected copy. No upload.
It cannot crack a password you do not know. If you have lost it, the file stays locked; that is the point.

Protection versus deterrence

A password stops someone from opening the file. A watermark does not stop anything, but "CONFIDENTIAL — for Anna, 21 Sep" across every page makes a leaked copy traceable. Use both for sensitive documents.

Add a watermark to PDFStamp a text watermark such as CONFIDENTIAL or DRAFT across every page of a PDF. Choose size, colour, opacity and angle. Runs in your browser.

All three tools run qpdf and pdf-lib in your browser; neither the file nor the password is sent anywhere.

Published 2026-09-21