Password Protect PDF

About Password Protect PDF

This tool adds password protection to your PDF files directly in your browser using industry-standard 256-bit AES (PDF 2.0 / R6 handler), with AES-128 and legacy RC4-128 available for older readers. You can set a user password (required to open the PDF) and an owner password (required to change permissions), and a live strength meter rates your open password. All encryption happens locally - your files are never uploaded to any server. See also our Compress PDF and Merge PDFs.

What is the difference between User and Owner passwords?

User Password (Open Password) is required to open and view the PDF. Owner Password (Permissions Password) controls what actions are allowed, like printing, copying, or editing. You can set one or both passwords.

What encryption is used?

This tool uses 256-bit AES encryption by default (the V5/R6 security handler defined in PDF 2.0), the industry standard for PDF security. You can also choose AES-128 or legacy RC4-128 for compatibility with older readers.

What is the difference between AES-256, AES-128 and RC4-128?

AES-256 (R6/V5) is the strongest and most modern option, supported by current versions of Adobe Acrobat, Chrome, Firefox, Edge and Preview. AES-128 (R4) covers Acrobat 7 and later. RC4-128 (R3) is a weaker legacy algorithm kept only for very old readers, scanners and multifunction printers (MFPs) that do not support AES. Choose the strongest level your recipients' software can open.

Are the permission restrictions actually enforced?

Permission flags (no printing, no copying, etc.) are advisory: they are honored only by compliant PDF readers, and they can be bypassed by non-compliant software. Crucially, if you set only a user password, that same password also acts as the owner password, so restrictions are trivially bypassable. To make permissions meaningful, set a distinct Owner Password that differs from the open password.

Is this safe for GDPR, HIPAA or confidential legal and financial documents?

Yes. All encryption runs entirely in your browser using JavaScript - your PDF and passwords never leave your device and are never uploaded to any server. This makes the tool suitable for confidential legal, financial and healthcare documents where files must stay on-device for GDPR or HIPAA compliance.

What happens if I lose the password?

There is no backdoor or recovery option. AES encryption is one-way: if you forget the password, the PDF cannot be opened or recovered. Store passwords in a password manager and choose a long, mixed-character password - the built-in strength meter helps you gauge it.

Can I set permissions without requiring a password to open?

Yes! You can set only an Owner Password to restrict actions like printing or copying, while still allowing anyone to open and view the PDF.

What permissions can I control?

You can control: Printing, Copying content, Modifying the document, Adding annotations, Filling forms, and Document assembly (inserting/deleting pages).

Is my PDF file safe?

Absolutely! All encryption happens directly in your browser using pdf-lib. Your PDF file is never uploaded to any server. Everything stays private on your device.

Can I remove password protection later?

To remove password protection, you'll need to open the PDF with the correct password in a PDF reader that supports removing encryption, such as Adobe Acrobat.

What is the maximum file size?

The maximum file size is 100MB. This ensures smooth performance in your browser.

Will this work with all PDF readers?

Yes! The encryption used is compatible with all major PDF readers including Adobe Acrobat, Chrome, Firefox, Edge, Preview (Mac), and most mobile PDF apps.