Protect PDF
Add your PDF or PASSWORD file, choose any options you need, and DOC321 prepares the PDF result for you.
Choose a PDF file
Add 256-bit password protection to a new PDF copy.
Use a strong password you can remember. The tool creates a separate encrypted copy.
Choose a PDF file to begin.
Add 256-bit password encryption to a PDF in your browser and download a separate protected copy.
Free Protect PDF
Works with PDF or PASSWORD
Get a usable PDF result
Free Protect PDF: Protect PDF or PASSWORD Online
Add 256-bit password encryption to a PDF in your browser and download a separate protected copy.
256-bit PDF encryption
Protect the new PDF copy with modern 256-bit encryption using QPDF in the browser.
One password to open
Choose the password readers must enter before opening the protected PDF.
Original file stays unchanged
The source PDF is never overwritten; the tool creates a separate protected copy.
How to Use Protect PDF
- 1Add PDF, PASSWORD
Choose the file or content you want to work with in the hero workspace, or drag it into the upload area.
- 2Choose your options
Set only what is necessary for the result you want.
- 3Run Protect PDF
Add password protection to a PDF
- 4Use PDF
Review the result, download it, or continue into a closely related workflow.
Protect PDF for Everyday Workflows
Security-focused task
Keep password, protection, and access changes separate from unrelated document edits.
Focused workflow
Everything on the page is organized around one job: add password protection to a PDF.
Clear source and result
Know what goes in as PDF and what you should expect back as PDF.
Built for everyday files
Use the tool for school, office, personal, client, publishing, and administrative document tasks.
Easy to review
Check the result before you download, share, submit, print, publish, or continue into another tool.
Easy next step
Related DOC321 tools stay close by when the finished file needs another conversion, edit, or document action.
FAQs About Protect PDF
How do I password protect a PDF?
Choose the PDF, enter and confirm an open password, then create and download the protected copy.
What encryption does this use?
The current tool requests 256-bit PDF encryption from QPDF.
Can you recover my password later?
No. Keep your password somewhere safe. The tool does not provide password recovery.
What does Protect PDF do?
Protect PDF is designed to add password protection to a PDF. The page keeps that task, the supported PDF input, and the PDF result together in one browser workflow.
Can I use Protect PDF online for free?
Yes. DOC321 provides Protect PDF as a free online browser tool so you can start the supported workflow from the page without installing a separate desktop application.
Document Work Made Easier
Finished with Protect PDF? DOC321 keeps related PDF, Word, image, spreadsheet, presentation, text, and document tools close so you can continue the workflow without starting over.
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