Password Protect a PDF
Add a password to a PDF with AES-256 encryption.
Free · No upload · 100% on your device
Add a password to a PDF
Choose a PDF, or drop it here.
No file-size or page limits. Nothing is uploaded.
You chose more than one PDF. What would you like to do?
100% on your device
How to use Protect PDF
- Choose your PDF, or drop it on the page.
- Adjust the settings in the side panel. The preview updates as you go.
- Select “Protect PDF”.
- Download the result. Your original file is left unchanged.
Private by design. Your files are processed in this browser tab and are never uploaded to KittySuite.
About Protect PDF
Add a password so a PDF cannot be opened without it. The file is encrypted with AES-256, the strongest standard PDF encryption, which current versions of Adobe Acrobat, Chrome, Edge, Firefox, macOS Preview and most phone readers support. Type the password twice to avoid a typo.
Keep the password safe: it cannot be recovered or reset. Optional restrictions on printing, copying and editing are flags that well-behaved PDF readers respect, not cryptographic protection, so rely on the open password for confidentiality. Encryption runs locally with qpdf compiled to WebAssembly; the PDF and password never leave this browser tab.
Protect PDF: frequently asked questions
How do I put a password on a PDF?
Choose the PDF, type a password of at least 6 characters twice and save. The PDF then asks for that password every time it is opened.
How strong is the encryption?
AES-256, the strongest standard PDF encryption, supported by current versions of Acrobat, Chrome, Edge, Firefox, macOS Preview and most phone readers.
What if I forget the password?
It cannot be recovered or reset. Keep it somewhere safe before sharing the file.
Can I block printing and copying?
Yes, but these restrictions are flags that most readers respect, not encryption. The open password is what keeps the content confidential.