Evaluating Client-Side Document Processing in Next.js: Architectural Trade-offs

Introduction When building document utility applications, developers inevitably face a critical architectural crossroad: Should file manipulation occur on a backend server, or directly within the user's browser? Historically, heavy lifting was always delegated to the server. However, with the rise of strict data privacy regulations (like GDPR) and the increasing power of modern browsers, client-side processing—often referred to as the Local-First approach—has become a highly attractive proposition. To evaluate the true viability of this architecture, I built a Next.js application designed to merge, split, and manipulate PDF documents entirely in the browser using JavaScript. The goal was simple: zero server compute costs and absolute data privacy. In this article, we will examine the mechanics of client-side PDF manipulation, walk through a core implementation using pdf-lib , and critically analyze the severe technical bottlenecks developers must consider before adopting this architect