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ConvertBox

Protect PDF with a password

Add AES-256 password protection to a PDF entirely in your browser. Set printing, copying, and editing restrictions without ever uploading your file.

🔒

Select a PDF file

Drop a PDF here or click to choose. Up to 50MB.

Max file size: 50MB

or drag and drop · press Enter to browse

How to Use

  1. Select a PDF file (max 50MB).
  2. Choose a strong password and confirm it.
  3. Pick encryption strength and toggle permissions.
  4. Click Protect PDF to download the encrypted copy.
  5. Verify the output file in your device's download folder.
  6. You can adjust settings and process new files immediately without any restrictions.

All processing is done in your browser, and files are never sent to a server.

Frequently Asked Questions

Encryption runs in your browser using qpdf compiled to WebAssembly. Your file and password never leave your device.
No. AES encryption is one-way without the password. Store passwords safely.
AES-256 uses a longer key and is more resistant to brute-force attacks. AES-128 is faster but still secure for most use cases.
Yes. The output uses standard PDF encryption that any modern PDF reader can prompt for.
No. All operations are processed entirely inside your browser's local sandbox using client-side APIs (like WebAssembly, pdf-lib, or HTML5 Canvas). Your files and data never leave your device.
The tool is completely free with no usage limits. However, since processing occurs in your browser's memory, we recommend keeping file sizes under 50MB (especially for heavy files like PDFs or videos) to ensure stability.
No. All tools on ConvertBox are 100% free. We do not insert watermarks, limit features, or require any registration or payment.
Yes. Once the page and its local library dependencies are loaded in your browser, the conversion logic runs completely offline without needing an active internet connection.

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