Upload a PDF, type a password, and download an encrypted copy that asks for that password every time it is opened. It is the usual way to send a payslip, a tax return, a medical report or a signed contract by email when you do not want whoever stumbles on the attachment to be able to read it.
The file is encrypted with AES-256, the strongest method the PDF standard defines. It opens normally in Adobe Acrobat and Reader, macOS Preview, and the built-in viewers in Chrome, Edge and Firefox, as long as the person has the password.
You can also decide whether the reader may print the document or copy text out of it. Editing, commenting and rearranging pages are always restricted in the protected file, while filling in form fields and screen-reader access remain allowed.
How to protect PDF
- Add your PDF. One file at a time, up to 100 MB. If it already has a password, remove that first with Unlock PDF.
- Enter a password. Between 4 and 128 characters. It is case-sensitive, so <code>Harbour</code> and <code>harbour</code> are different passwords.
- Choose the permissions. Allow printing and Allow copying text are both on by default. Untick either one to restrict it.
- Protect and download. The encrypted file is saved with <code>-protected.pdf</code> on the end of the original name.
What the password does, and what the permissions do
These are two different kinds of protection and it is worth knowing which is which. The open password is real encryption. Without it, the contents of the file are scrambled data; no reader, browser or script can display the pages, because the key needed to decrypt them is derived from the password.
The printing and copying permissions work differently. Once someone has opened the file with the password, the encryption has done its job, and the permissions are a flag that tells the reader what to allow. Acrobat, Preview and the browser viewers all respect them, so the print button or text selection is greyed out. Software written to ignore the flag can still print or copy, so treat these settings as a firm request to well-behaved readers rather than a guarantee.
Restrictions in a PDF are normally controlled by a second, separate owner password. This tool generates a random one and does not show it to anyone, so the restrictions cannot be lifted through the usual permissions route in a PDF editor. Anyone who should be able to edit the document needs the unprotected original.
Choosing and sending the password
Length matters more than odd symbols. A passphrase of four or five random words, such as kettle orbit wattle seventeen, is far harder to guess than an eight-character mix like P@ssw0rd, and much easier to read out over the phone. The tool accepts up to 128 characters, so there is room for a long one.
Send the password through a different channel from the file. If the PDF goes by email, send the password by text message or tell the person in a call. A password written in the same email as the attachment protects nothing if that email is forwarded or the mailbox is compromised.
There is no way to recover a forgotten password. That is the point of encryption: if the password could be recovered, so could the file by anyone else. Keep it in a password manager, and keep an unprotected copy of the original somewhere safe if you will need to edit it later. OzPDF does not store the password; it is left out of the anonymous usage history.
Compatibility and limits
Older readers. AES-256 encryption (PDF 2.0, revision 6) is supported by Adobe Reader 9 and every version since, which means anything from 2008 onwards, plus macOS Preview and current Chrome, Edge and Firefox. Readers older than that cannot open the file at all. In practice this only comes up with very old office machines or embedded systems.
Files that already have a password are refused. To change a password, open the file with Unlock PDF using the current password, then run the unlocked copy through Protect PDF with the new one.
Do other edits first. Once a file is encrypted, other tools need it unlocked before they can work on it. If you also want to merge, compress or watermark the document, do that first with Merge PDF, Compress PDF or Watermark PDF, and add the password as the last step.
Questions people actually ask
How do I password protect a PDF for free?
Upload the PDF here, type a password between 4 and 128 characters, choose whether printing and copying are allowed, and download the protected copy. It is encrypted with AES-256 and will ask for the password whenever it is opened in Acrobat, Preview or a web browser.
Can I stop people printing or copying text from my PDF?
Yes. Untick Allow printing or Allow copying text before you protect the file. Acrobat, Preview, Chrome, Edge and Firefox respect these settings. They are enforced by the reader rather than by the encryption, though, so software written to ignore them can still print or copy once the file is open.
What happens if I forget the password to my PDF?
The file cannot be opened. There is no recovery option, because a password that could be recovered would not be real protection, and OzPDF does not store passwords. Keep the password in a password manager and hold on to an unprotected copy of the original if you might need it.
How do I change the password on a protected PDF?
Files that already have a password are refused, so it takes two steps. First remove the existing password with Unlock PDF, which needs the current password. Then upload the unlocked copy here and protect it with the new password you want to use.
Will a password-protected PDF open on any computer or phone?
It opens in Adobe Acrobat and Reader 9 or later, macOS Preview, and the built-in PDF viewers in Chrome, Edge and Firefox. Only very old readers released before 2008 cannot handle AES-256 encryption. The person opening it will still need the password.