Cachety

Cachety is a free, open-source web application that lets you watermark PDFs and images on your own device without uploading files to a server. It includes features like personalized watermarks, traceable copies, secure password protection with AES-256 encryption, and removal of hidden data. Designed with privacy and security in mind, it runs entirely client-side in the browser and supports multiple file types, including HEIC photos on mobile devices.