Protect PDF
Add a password to your PDF.
Drop your PDF here
or click to browse
Up to 10 MB · 20 pages
Encrypted with 256-bit AES, entirely in your browser — the file and password never leave your device.
How to password protect a pdf
Protecting a PDF encrypts it with a password using AES-256, the strongest encryption the PDF specification defines. Without the password the file cannot be opened or its contents recovered.
- 1
Choose your PDF
Drop the document you want to encrypt.
- 2
Set a password
Enter the password that will be required to open the file. Choose something you can recover — there is no reset.
- 3
Download
Click Protect and the encrypted PDF downloads.
Your files never leave your device
Unlike most online PDF tools, this one uploads nothing. Everything runs inside your browser, so your document is never transmitted, never stored on a server, and never seen by anyone but you. Once the page has loaded you can disconnect from the internet entirely and the tool still works.
Frequently asked questions
- Is my password sent anywhere?
- No. The password never leaves your browser. The document is encrypted on your own device, so neither the password nor the file is ever transmitted.
- What encryption is used?
- AES-256 under the PDF 2.0 standard security handler (revision 6), which is the strongest option the PDF specification defines and is accepted by every modern reader.
- What if I forget the password?
- The file cannot be recovered. That is the point of real encryption — there is no backdoor, and we cannot help because we never had the file or the password.
- Can I protect an already-protected PDF?
- Remove the existing password with the Unlock tool first, then protect it again with the new password.
Related tools
DinoPDF — every tool runs in your browser. Nothing is uploaded.