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1d agoMerge PDF
PDF · 3 files
Protect PDF Online Free
Add a password to your PDF to prevent unauthorized access.
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How to use Protect PDF?
- Select a PDF that is not already password-protected (or drag and drop it).
- Enter a strong password (or check Manual password to skip the strength meter) and confirm it.
- Optionally check Download password with PDF to get a ZIP with the locked file and a password text file.
- Click Lock PDF and download your protected file.
FAQs
Yes. Protect PDF runs entirely in your browser on your device. Your PDF is not uploaded to our servers for processing, and we do not store your file or password. The site loads over HTTPS like any secure webpage, but the protection step itself happens locally.
PaperStack never stores your password, so we cannot recover it for you. Keep a copy in a safe place. If you lose the password, you will need the original unprotected PDF (or another backup) to create a new protected version.
Not in this tool. Protect PDF requires a password (minimum 4 characters) and applies standard encryption together with permission settings. To use only restrictions without an open password, you would need different software that supports that workflow.
The protected file requires your password to open. Printing is allowed at high resolution; copying, editing, annotating, form filling, and document assembly are restricted, while content accessibility for assistive tools remains enabled—matching the fixed policy built into PaperStack Protect PDF.
It uses standard PDF password encryption, so it should open in common apps such as Adobe Acrobat, Preview on Mac, and most browser PDF viewers, as long as they support encrypted PDFs. Very old or unusual viewers might behave differently.
There is no separate server limit because files are processed in your browser. Very large PDFs use more memory and may be slower or fail on low-powered devices; typical document sizes usually work fine.
Yes. If you know the password, use PaperStack’s Unlock PDF tool to decrypt the file and lift the restrictions.
Use Unlock PDF first with the current password to get an unprotected copy, then use Protect PDF on that file with your new password.
Yes. It’s free to use with no sign-up required.
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Built for every tool
Why use PaperStack?
The same benefits apply to every tool—including Protect PDF.
Secure & private
Your files are processed in your browser on your device—not sent to our servers for processing or kept on our systems. Sensitive documents stay under your control.
100% free
No hidden fees, no premium tiers, and no usage limits. Use PaperStack for personal or business work—no account required.
Fast processing
Tasks run locally in your browser so you get results quickly—often in seconds—without waiting on a remote queue, even for larger files your device can handle.
Works everywhere
No software to install. Open PaperStack in any modern browser on Windows, Mac, Linux, iOS, or Android and use the tools you need.
PDF Tools
Other tools
Same privacy-first workflow — every tool runs in your browser.
PDF Editor
Edit PDFs: text, highlight, draw, sign, and manage pages
Merge PDF
Combine multiple PDFs into one
Split PDF
Split PDF into separate pages
JPG to PDF
Convert images to PDF
IMG to PDF
Convert images to PDF
PNG to PDF
Convert PNG to PDF
WORD to PDF
Convert Word to PDF
Compress PDF
Reduce PDF file size
Dummy PDF
Download or generate dummy PDF files by page count or exact size.
Remove pages
Select and remove the PDF pages you don't need.
Extract pages
Keep only the pages you choose in a new PDF.
Extract images
Pull embedded images out of a PDF.
Organize PDF
Sort, add and delete PDF pages.
Reverse PDF
Flip the order of all pages.
Insert Blank Page
Use Insert Blank Page
HTML to PDF
Use HTML to PDF
PDF to JPG
Each page as JPEG
PDF to PNG
Each page as PNG
PDF to images
Choose JPG, PNG, or WebP
Extract Text
Use Extract Text
Rotate PDF
Use Rotate PDF
Add page numbers
Use Add page numbers
Add watermark
Use Add watermark
Crop PDF
Use Crop PDF
Unlock PDF
Remove password protection from PDFs.
Compare PDF
Use Compare PDF
Privacy-first
Safe in our hands
PaperStack takes security very seriously. Remember that your files stay on your device—processing runs in your browser, and we don’t store your documents on our servers.
No cloud uploads
Your document never leaves this device for processing.
Browser-only processing
Merge, convert, and compress run locally in your tab.
Nothing stored on our servers
We don’t keep copies of your files after you close the page.
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