Real AES-256 PDF encryption
Encrypt a PDF with an opening password using AES-256. Processing and passwords stay on your device.
YOUR DOCUMENT. A PASSWORD AT THE DOOR.Keep access
Lock PDF
Keep access
in the right hands.
Encrypt a PDF with an opening password using AES-256. Processing and passwords stay on your device.
- Choose a file
- Adjust settings
- Review & save
Choose your PDF
Select one PDF from your device. The document is opened locally without a processing-server upload.
Adjust and review your settings
The tool encrypts the PDF with AES-256 and an opening password. A secure random owner key is generated locally. Use a modern PDF viewer and choose a strong unique password; tooldu.com cannot recover it.
Apply and download your PDF
Apply your settings, inspect the downloaded result and keep the original separately. Save your password separately; tooldu.com cannot recover it. Use a modern PDF viewer. Existing digitally signed and PDF/A documents require a suitable unsigned, non-archival copy.
Before you start
350 MB input/output · Up to 150 pages per PDF. Save your password separately; tooldu.com cannot recover it. Use a modern PDF viewer. Existing digitally signed and PDF/A documents require a suitable unsigned, non-archival copy.
30-minute trial. Continue with a paid pass or an eligible member trial.
You get 30 minutes to try the tools that need access, without creating an account. Once that window ends, wait at least one hour before starting another. Opening an eligible trial tool starts the next window. Time keeps running while you are away. The nine free tools have no session timer.
Files stay on your device30 minutes free to start
YOUR PRIVATE PDF WORKSPACE
Drop your PDF. Start something useful.
A clearer way to finish your PDF.
Drag and drop a PDF here, or choose from your device.
350 MB per file · Up to 150 pages per PDFKnow the limits. 350 MB per file and output · Up to 150 pages per PDF. Save your password separately; tooldu.com cannot recover it. Use a modern PDF viewer. Existing digitally signed and PDF/A documents require a suitable unsigned, non-archival copy. Device memory limits apply.
Practical controls. A result you can use.
Password confirmation and secure random owner key
Purposeful controls with clear limits, designed for both touch and keyboard.
Original text and page content retained
Process your document on this device and review the real result before sharing.