Protect PDF

Password protect a PDF online with AES-256 encryption, and optionally block printing, copying or editing. Free and private: the PDF never leaves your browser.

Files are processed in your browser and never uploaded.

Uses AES-256 encryption (PDF 2.0). Anyone opening the PDF must enter the password.

How to password protect a PDF

  1. Drop the PDF onto the drop zone above, or click to choose it. The tool protects one file at a time.
  2. Type a Password. Anyone who opens the PDF will have to enter it before a single page is shown.
  3. Optionally fill in Owner password for permissions. This second password unlocks full rights over the document, so keep it to yourself.
  4. Choose what readers may do: Allow printing and Allow copying text are ticked by default, Allow editing is not.
  5. Click Protect PDF and download the result. A file called contract.pdf is saved as contract-protected.pdf.

The encryption is done by pdf-lib inside your browser. Neither the document nor the passwords are uploaded or sent anywhere.

How PDF password protection works

The tool encrypts the PDF with AES-256, the method defined in PDF 2.0 (security handler revision 6). Every page, image and text stream is encrypted, and a key derived from your password is needed to decrypt them. Without the password the file is unreadable, not merely hidden behind a prompt.

A PDF can carry two passwords, and they do different jobs:

Password (to open)Owner password
PurposeNeeded to open and read the documentGrants full rights, ignoring the permission settings
If left blankRequired in this toolThe open password doubles as the owner password, so anyone who can open the file has full rights
Give it toThe people who should read the fileNobody but yourself

The printing, copying and editing checkboxes are permission flags, not a second layer of encryption. Adobe Acrobat, browsers and other compliant viewers respect them, but a non-compliant program can ignore them once the file is open. Treat permissions as a clear statement of how the document should be used, and rely on the open password for confidentiality.

Compatibility

AES-256 PDFs open in Adobe Acrobat and Reader X or later, Chrome, Edge, Firefox, macOS Preview and other current viewers. Very old readers that only understand RC4 or AES-128 encryption cannot open them. If a recipient reports that the file will not open at all, an outdated reader is the most likely cause.

Tips

  • The strength of the encryption depends on the password. A long random one from the password generator is far harder to guess than a word or a date.
  • Finish all other edits first. Encrypted PDFs cannot be processed further, so merge, compress or watermark the document before you protect it.
  • A PDF that is already encrypted must be opened with Unlock PDF before you can set a new password.
  • Sending several documents together? Password Protect Any File packs them into one encrypted ZIP.
Tip: Send the password through a different channel from the file, for example by phone or text message when the PDF goes by email. Someone who intercepts one does not automatically get the other.

Frequently asked questions

What happens if I forget the password?

The document cannot be recovered. Nothing on this site cracks or guesses passwords, and AES-256 is designed so that nobody can open the file without the correct one. Keep the unprotected original, or store the password in a password manager.

Do I need an owner password?

Only if the permission settings matter to you. Without one, anyone who knows the open password also has owner rights and the printing, copying and editing restrictions have no practical effect.

Can readers still print the PDF?

Yes, by default. Untick Allow printing to ask compliant viewers to disable printing for everyone who opens the file with the regular password.

How do I change the password later?

Remove the current password with Unlock PDF, then protect the unlocked file again with the new password.

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