What encryption strength is used?
The tool uses qpdf's 256-bit encryption mode for the generated PDF.
Encrypt PDF
Add a 256-bit password to a PDF and optionally restrict printing or content copying.
PDFAPIStatic billingFree
Upload PDF files
qpdf handles structure-level PDF transformations. It does not OCR, extract text, or edit page content.
PDF only. Each file must be under 20MB.
Selected files
0No PDF selected yet.
The output uses qpdf 256-bit encryption. Permission flags depend on PDF reader support.
About this tool
Add a 256-bit password to a PDF and optionally restrict printing or content copying.
PDFAPIStatic billingPublic
Tool facts
Execution type: API
Credit cost: Free
Billing unit: 1 protected file
Supported locales: English, Chinese
Last updated: Apr 14, 2026
Related content
Published articles and notes currently linked to this tool.
No published content is linked to this tool yet.
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Frequently asked questions
Do permissions guarantee perfect protection?
No. PDF permission flags depend on reader support. They are useful controls, but they are not a substitute for access control.
How to use this tool
1
Upload a PDF
Choose the PDF you want to protect.
2
Set passwords
Enter an open password and optionally an owner password.
3
Download encrypted PDF
Run qpdf and download the password-protected result.