PDF Protect
Password protect a PDF with AES-256 encryption using our PDF Protect tool. Enter the password readers need to open the file and, if you like, a separate owner password, and qpdf encrypts every page, image and attachment with the strongest standard PDF encryption. Upload a PDF up to 10 MB and 200 pages, such as a contract, statement or report you need to send safely by email or share online.
Frequently asked questions
How do I password protect a PDF?
Upload the PDF, enter the password readers will need in the Open Password field and click Protect PDF. The download asks for that password in every PDF viewer before it shows any page.
Which encryption is used?
The file is encrypted with AES-256, the strongest method the PDF standard defines (security handler revision 6). It is supported by Adobe Acrobat and Reader X and newer, browsers, macOS Preview and current mobile apps.
What is the owner password for?
The owner password unlocks full control over the file, such as changing its protection. If you leave it empty, a random owner password is generated and not shown, and the open password alone opens the file with every permission.
Can I also restrict printing or copying?
This tool grants every permission once the file is open. To block printing, copying, editing or page assembly, use PDF Permissions, which sets those restrictions with an owner password.
How long can the password be?
A password can have up to 127 bytes, which is the limit of AES-256 PDF encryption. Long passphrases of several words are the safest choice, since short passwords can be guessed by brute force.
Can I protect a PDF that already has a password?
No. The tool refuses files that are already encrypted. Remove the existing protection with PDF Unlock using its password first, then protect the unlocked file again.
What if I forget the password?
There is no way to recover it. AES-256 encryption cannot be bypassed, so keep the password somewhere safe or keep an unprotected copy of the original.
Does encryption change the content of my PDF?
No. Pages, fonts, images, links and form fields stay the same; they are only stored encrypted. The file grows only slightly, by a few bytes for each encrypted object.
What are the limits?
You can protect one PDF of up to 10 MB with at most 200 pages per request. The download keeps the original name with -protected added.
Are my passwords stored?
No. The passwords are used only to encrypt the file in memory during the request. They never appear in the result, the logs or anywhere else, and the file is discarded afterwards.