Protect PDF

Honest answer: this isn't available yet, on purpose. Here's why, and what to use instead.

We'd rather tell you this clearly than fake a "protected" file that isn't actually encrypted.

Why we don't offer this

Real PDF password protection uses standardized encryption (RC4 or AES, applied to every string and stream in the file per the PDF specification). The open-source library this site uses for reading and writing PDFs client-side (pdf-lib) doesn't implement PDF encryption. Hand-rolling encryption code ourselves is exactly the kind of thing that's easy to get subtly wrong — and a PDF that looks password-protected but isn't correctly encrypted would be worse than no protection at all, since it would give you false confidence.

Rather than ship something that might not actually protect your document, we're leaving this tool out until we can do it properly — for example, with a well-vetted encryption library, or a review process we're confident in.

What to use instead right now

Microsoft Word / Adobe Acrobat: both can export or save a PDF with a password directly (File → Save As / Export → PDF, with a password/security option).
macOS Preview: File → Export as PDF → Show Details → Permissions, lets you set an owner and open password.
LibreOffice: Export as PDF has a built-in "Set open password" option using real AES encryption.

See tools that are ready Read more in the FAQ