Pick the right mode
Use client when you want files to stay interpretable only inside PDFZen's paired unlock flow. Use server when you need a normal passworded PDF and your host runs the protect API.
Privacy-first PDF suite
Protect a PDF with a password
Client encryption keeps the PDF inside encrypted JSON for our unlock tool. Server mode produces standard PDF passwords when your backend exposes qpdf.
Runs in your browser when possible; some options use our servers or a cloud converter.
Client mode creates an encrypted JSON you can unlock locally. Server mode uses qpdf for standard PDF passwords.