The latest articles on DEV Community by TimelyUps (@timelyups). https://dev.to/timelyups https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F4170278%2F304ed235-c168-4b11-b434-63b8f45682b9.png https://dev.to/timelyups en TimelyUps Sat, 24 Oct 2026 05:21:56 +0000 https://dev.to/timelyups/i-built-free-pdf-tools-that-run-100-in-the-browser-no-server-no-uploads-12ik https://dev.to/timelyups/i-built-free-pdf-tools-that-run-100-in-the-browser-no-server-no-uploads-12ik <p>Pakistan's news readers needed simple, trustworthy utilities — merge a PDF, turn photos into a PDF, pull images out of a PDF — without uploading personal documents to a random server. So I built them as a fully client-side toolset on our news site. Here is how, and what I learned.</p> <h2> The architecture: everything in the browser </h2> <p>The stack is deliberately boring: two CDN libraries, zero backend.</p> <ul> <li> <strong>pdf-lib</strong> handles merge and JPG-to-PDF assembly.</li> <li> <strong>pdf.js</strong> (Mozilla's renderer) handles PDF-to-JPG page rasterization. Every operation runs in the browser with chunked async steps, so the UI never freezes on a 50-page document. The key privacy property: <strong>files never leave the device</strong>. There is no upload endpoint at all.</li> </ul> <h2> Lessons from shipping to real users </h2> <p><strong>1. Memory is the real limit, not CPU.</strong> Rasterizing PDF pages at print resolution eats RAM fast. I cap export resolution and process pages sequentially instead of in parallel.<br> <strong>2. Mobile Safari is the QA department.</strong> Half our traffic is mobile. pdf.js rendering on older Android WebViews needed explicit fallbacks for missing OffscreenCanvas support.<br> <strong>3. Small UX details carry the product.</strong> A drag-and-drop zone, per-file remove buttons, and a visible "your files never upload" notice did more for trust than any feature.<br> <strong>4. No-backend means no bills.</strong> Hosting is a static page. The tools cost essentially nothing to run at scale — a meaningful property when your audience is price-sensitive students and job applicants.</p> <h2> Try it </h2> <p>The tools are live and free: <a href="https://timelyups.com/tools/pdf-tools/" rel="noopener noreferrer">TimelyUps PDF Tools — merge PDFs, JPG to PDF, PDF to JPG, all in your browser</a>. Feedback and bug reports welcome in the comments.</p> <p><em>I run <a href="https://timelyups.com/" rel="noopener noreferrer">TimelyUps</a>, a Pakistan-focused digital news outlet where we also ship free online tools for our readers.</em></p> webdev javascript pdf opensource