Protect PDF

Password-Protect & Encrypt PDFs Online for Free

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Drag & drop PDF files here, or browse

PDF files only

How It Works

Add PDF files Drag and drop your PDF files or click to browse. Protect one or multiple files at once.
Set a password Enter a password. Optionally set a separate owner password and configure permissions under Advanced Options.
Encrypt Click Protect. AES-256 encryption runs locally in your browser - nothing is uploaded.
Download Download your encrypted PDFs individually or as a ZIP archive.

Features

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AES-256 Encryption Uses the strongest PDF encryption standard (AES-256, Revision 6) - the same algorithm used by financial institutions. All crypto runs via the browser's native Web Crypto API.
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100% Private Your PDFs and passwords never leave your device. No server upload, no cloud processing, no data retention. Encryption happens entirely in your browser.
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Fine-Grained Permissions Control exactly what recipients can do: printing, copying text, modifying content, filling forms, annotating, and more.
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Batch Encryption Encrypt multiple PDF files at once with the same password and settings. Download individually or as a ZIP.
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Dual Password Support Set a user password to restrict opening and an owner password to control permissions - standard PDF security model.
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Completely Free No trial limits, no watermarks, no hidden fees. Just encrypt and download.

Supported Formats

FAQ

What encryption does this tool use?

Apparatus uses AES-256 encryption (PDF 2.0, Revision 6) - the strongest standard supported by PDF readers. All cryptographic operations use the browser's native Web Crypto API, which is hardware-accelerated on most devices.

Is it safe to encrypt PDFs in my browser?

Yes. Your files never leave your device. Encryption runs entirely in your browser using hardware-accelerated Web Crypto APIs - no server ever sees your documents or passwords.

What is the difference between user password and owner password?

The user password (or open password) is required to open and view the PDF. The owner password controls permissions like printing, copying, and editing. If you only set a user password, it is used for both roles.

Can I set permissions without requiring a password to open?

This tool requires a user password for strong security. Owner-password-only restrictions (which allow anyone to open but restrict actions) can be trivially bypassed by most PDF tools, so a user password is always recommended for meaningful protection.

Will encrypted PDFs work in all PDF readers?

AES-256 (R6) is supported by Adobe Acrobat X and later, Chrome and Edge built-in viewers, Preview on macOS, and most modern third-party readers. Very old readers that only support 40-bit RC4 encryption will not be able to open the file.

Can I encrypt multiple PDFs at once?

Yes. Add as many PDF files as you like. They will all be encrypted with the same password and permission settings, and can be downloaded individually or as a ZIP archive.

How It Works

Features

Supported Formats

FAQ

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