Protect PDF with a Password
Encrypt a PDF so it can only be opened with a password, and optionally block printing or copying.
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About Protect PDF
Lock a PDF before you email or share it. The file is encrypted with AES-256, the standard every PDF reader supports, so it can only be opened with the password you set. You can also allow readers to open it but stop them printing, copying text or editing. Encryption happens on your device with qpdf, a widely used open-source PDF library, so neither the file nor the password is ever sent anywhere.
How to password protect a PDF
- Drop the PDF into the box, or click it to choose it.
- Type the password that will be needed to open the file, twice.
- Optionally set an owner password and choose what readers may do.
- Click “Protect PDF”, then save the encrypted file.
Everything happens in your browser; nothing is uploaded. Very large files (over ~100 MB) can be slow on phones.
Frequently asked questions
Is my PDF or my password uploaded?
No. TrustPDF runs entirely in your web browser using JavaScript. Your file and your password are read and processed on your own device and is never sent to a server. The site's Content-Security-Policy does not allow the page to send anything to any other site, and you can check the open-source code on GitHub.
How strong is the encryption?
AES-256, the strongest encryption defined in the PDF standard, as used by Adobe Acrobat. A long password matters more than anything: a short or common one can be guessed.
What is the owner password for?
The owner password unlocks the restrictions (printing, copying, editing). Readers who only have the open password are bound by them. If you leave it empty, a random owner password is set that nobody knows, so the restrictions cannot be switched off with the open password. Note that restrictions rely on the PDF reader honouring them; only the open password actually encrypts the content.
What if I forget the password?
There is no way to recover it; the content is encrypted with it. Store the password somewhere safe, such as a password manager.
Can old PDF readers open AES-256 files?
Readers released since about 2009 (Adobe Reader 9 or newer, all current browsers) can. Very old readers may not.
