What does Protect PDF do?
Encrypt a PDF with a password to prevent unauthorized opening.
Protect PDF accepts PDF files, and produces PDF output.
Your PDF files are processed locally in your browser — they are never uploaded to our servers.
How to use Protect PDF
- 1Drag and drop your file onto the upload area, or click “Choose file”.
- 2Adjust the protect pdf settings to suit your needs.
- 3Click the main action button and wait a moment while it is processed on your device.
- 4Preview the result and download your PDF file.
Supported formats
- Input
- Output
Frequently asked questions
Is Protect PDF free?
Yes. Protect PDF is completely free with no sign-up and no watermarks.
Are my files uploaded?
Your PDF files are processed locally in your browser — they are never uploaded to our servers.
Is there a file size limit?
Free usage supports files up to 200 MB. Because processing happens on your device, very large files depend on your device's available memory.
How strong is the encryption?
PDFs are encrypted with AES-256 by qpdf, the same standard used by Adobe Acrobat. The password is never sent anywhere.