Protect PDF
Protect your PDF with strong password encryption completely offline.
Password Protection
Selected: document.pdf
Encrypting document locally using AES-GCM...
All calculations are run locally inside your browser context. Please do not close this tab.
Task Completed successfully
Your file is ready to download or continue into another tool below.
Continue Workflow - Recommended Next Steps
Use your newly generated file directly in another tool without re-uploading.
Executed 100% locally on your browser
When you upload files, they are read as binary arrays in your browser's sandboxed RAM. We use high-performance WebAssembly to execute tasks locally, never sending files to any server.
Secure your confidential files. Apply strong password encryption (RC4 or AES) directly inside your browser tab to prevent unauthorized opening or editing.
How to use our free Protect PDF tool
Select PDF document
Select the PDF file you wish to secure by browsing your folders or dragging it in.
Set a strong password
Type your desired password in the security panel. Choose a combination of letters, numbers, and symbols.
Encrypt locally
Click the 'Encrypt PDF' button. The WebAssembly engine compiles the PDF with local cipher encryption.
Download locked PDF
Save the protected PDF file. It will require the password before any PDF reader will open it.
Why choose PDFVoid Protect PDF?
RC4 / AES Security
Applies standard PDF encryption parameters to lock document content streams securely.
Complete Confidentiality
No passwords or unencrypted files are ever transmitted, ensuring absolute safety for keys.
Universal Lock Compatibility
The password protection is fully compliant with Adobe Acrobat, PDF readers, and mobile OS viewers.
Frequently Asked Questions
What happens to the password I type?
Your password stays strictly inside your browser's execution stack. It is used to generate the cryptographic keys to encrypt the PDF array, and is never logged or sent to any server.
Can anyone open my protected PDF without the password?
No. The PDF will be locked using standard compliance algorithms. Standard PDF software will refuse to decrypt the document streams without the correct password.
Is this tool free to use?
Yes, like all PDFVoid tools, securing your PDFs is completely free, unlimited, and runs client-side.
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