How to password protect a PDF for free without installing any software. In this tutorial, I'll show you how to add password protection to your PDF files using free online tools and built-in features on Windows PC, Laptop, iPhone, Android, and Mac. This means you can secure sensitive documents and restrict access to your PDFs in just a few clicks. I also show you how to easily encrypt a PDF file for free. To do this we use a tool I built called PDFGadget. PDFGadget allows you to password protects