A year ago, I got fed up with online PDF tools. Every time I needed to merge a contract or compress a resume, I had to upload my file to someone else's server. As a developer, I knew exactly what that meant — my file was sitting on a cloud server I didn't control, processed by code I couldn't see, and potentially logged or cached somewhere I couldn't audit. So I decided to build an alternative: a PDF toolkit that runs entirely in the browser . No server uploads. No registration walls. No privacy trade-offs. This post is a recap of the technical decisions, the libraries I chose, and the traps I fell into along the way.…