Is my PDF uploaded to a server?

No. All encryption is performed locally in your browser using the pdf-lib library. Your file never leaves your device.

What encryption is applied?

pdf-lib applies 128-bit RC4 encryption, the standard level supported across all major PDF readers.

What is the difference between user and owner passwords?

The user password (open password) is required to open the document. The owner password (permissions password) controls restrictions like printing or copying. Both are optional but at least one should be set.

Can I password-protect an already-encrypted PDF?

No. Remove the existing password first using a PDF unlock tool, then apply the new password here.

Will the encryption work in all PDF readers?

Yes. 128-bit RC4 is widely supported by Adobe Acrobat, Preview (macOS), Foxit, Chrome, and all standard PDF readers.

Is there a file size limit?

There is no enforced server limit since processing is local. Very large PDFs (100 MB+) may be slow depending on your device.

PDF Password Protect

Name: PDF Password Protect
Availability: InStock
Author: Nham Vu

Upload a PDF, set a password, and download an encrypted copy — everything runs in your browser, no file is ever uploaded.

Encryption Settings

Click or drag a PDF here

Only PDF files are accepted

User Password (required to open)

Owner Password (optional — controls permissions)

Allow Permissions

Printing Copying text and images Modifying content Adding annotations

File Status

No PDF loaded

Upload a PDF on the left to begin

Summary

Upload a PDF, set a password, and download an encrypted copy — everything runs in your browser, no file is ever uploaded.

How it works

Click or drag a PDF file into the upload area.
Enter a user password — anyone opening the PDF will need this.
Optionally enter an owner password to restrict printing and copying.
Choose which permissions to allow (printing, copying, etc.).
Click "Encrypt and Download" to save the protected PDF.

Use cases

Securing confidential documents before emailing them.
Protecting invoices or contracts with a shared password.
Restricting copying of proprietary PDF content.
Locking draft reports before sending for review.
Preventing unauthorized printing of sensitive files.
Adding access control to legal or financial documents.

Frequently Asked Questions

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Last updated: 2026-05-29 · Reviewed by Nham Vu