How to Password Protect a PDF
To password protect a PDF, encrypt it with an open password so nobody can view it without typing that password. PDFDEN's free tool to password protect a PDF uses AES-256 encryption and runs in your browser. You can also restrict printing, copying and editing.
Protect PDF: Add a password to a PDF. Free, and your file never leaves your device.
Open Protect PDFSteps
Open Protect PDF and drop in your PDF.
Type the open password. Pick something long that you can share safely with the recipient.
Optionally turn on restrictions to block printing, copying text or editing.
Run it and download the encrypted PDF. Open it once to check the password works.
Choose a password that holds up
AES-256 is strong encryption, but a short or common password can still be guessed. A long passphrase of several unrelated words is harder to break than a short string of symbols.
Send the password through a different channel than the file. If the PDF goes by email, share the password by text message or phone.
There is no reset. If you forget the password, the file cannot be opened, so keep an unencrypted original somewhere safe.
Restrict printing, copying and editing
Restrictions are an extra layer on top of the open password. They tell PDF readers to block printing, text copying or changes.
Know their limits. Most readers respect them, but restrictions are enforced by the software, not by the encryption itself. Treat them as a deterrent. For content that must never be seen, remove it with Redact PDF before sharing. The PDF redaction guide explains why a black box drawn on top is not enough.
Protect PDF: Add a password to a PDF. Free, and your file never leaves your device.
Open Protect PDFPassword protect a PDF on Mac or with Word
On a Mac, Preview can add a password when you export. Open the PDF, choose File > Export, turn on the encryption option, enter a password and save.
Windows has no built-in PDF encryption. If the document starts in Microsoft Word, you can choose File > Save As, pick PDF, open Options and tick Encrypt the document with a password. For an existing PDF, the PDF password tool is the quickest route on any system.
Clean the file before you lock it
A password protects the content, not the hidden details. PDFs often carry an author name, the software used and creation dates. Clear them with the PDF Metadata Editor first, then encrypt. It can remove all of it in one click.
Check the pages too. If only part of the document is private, redacting that part may be better than locking the whole file, since the recipient can then forward the rest freely. To remove protection later, see how to remove a password from a PDF.
Who can open a password-protected PDF
Anyone with the open password, in almost any PDF reader. AES-256 is supported by current versions of the common readers on computers and phones, including the ones built into web browsers.
Very old PDF software may not open AES-256 files. If a recipient reports an error, ask them to try a current browser before you weaken the protection.
The file stays encrypted wherever it goes. Copying it to a USB stick, a shared drive or an email attachment does not remove the password. To send it to someone without the password later, create an unlocked copy with Unlock PDF and lock the new version with the PDF encryption tool again when needed.