The latest articles on DEV Community by Basil Aslam n p (@basilaslamnp). https://dev.to/basilaslamnp https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F3976211%2Fdba5163b-4d51-4fe8-98fa-b262079d3894.jpg https://dev.to/basilaslamnp en Basil Aslam n p Tue, 09 Jun 2026 14:53:36 +0000 https://dev.to/basilaslamnp/i-built-30-file-tools-that-run-entirely-in-your-browser-no-server-no-uploads-20n8 https://dev.to/basilaslamnp/i-built-30-file-tools-that-run-entirely-in-your-browser-no-server-no-uploads-20n8 <p>Most "free online tools" sites have the same dirty secret: when you merge a PDF or compress an image, your file gets uploaded to their server. For anything sensitive — contracts, IDs, personal photos — that's a problem most people never think about.</p> <p>So I built <a href="https://useonlinetools.com" rel="noopener noreferrer">UseOnlineTools</a> as an experiment: a tools site where <em>nothing</em> touches a server. Every operation runs client-side in the browser.</p> <h2> The stack </h2> <ul> <li> <strong>Astro</strong> — ships zero JS by default, each tool is an island, great Core Web Vitals</li> <li> <strong>WASM + <code>pdf-lib</code> / <code>pdf.js</code></strong> — PDF operations (merge, split, compress, rotate, convert)</li> <li> <strong>Canvas + WASM codecs</strong> — image work (compress, resize, HEIC→JPG, PNG→WebP, EXIF stripping)</li> <li> <strong>Pure JS</strong> — dev tools (JSON formatter, regex tester, JWT decoder, hashing, UUIDs)</li> <li> <strong>Cloudflare Pages</strong> — fully static hosting, near-zero ops cost</li> </ul> <h2> The interesting constraint </h2> <p>Deciding what <em>can't</em> be done client-side. Anything needing a rate-limited third-party API or heavy video transcode got cut.</p> <p>The rule became: <strong>if a tool needs a backend, it doesn't belong on this site.</strong> That constraint is also the privacy guarantee and the cost model — all three are the same decision.</p> <h2> A few things I learned </h2> <ul> <li> <strong>HEIC decoding in the browser is genuinely painful.</strong> The WASM decoder is large and you have to lazy-load it.</li> <li> <strong>"Your file never leaves your device" is hard to <em>communicate</em>.</strong> Users don't believe it by default. Still working on how to surface that trust.</li> <li> <strong>Static-first means SEO content and the tool can coexist</strong> on one fast page without a framework fighting you.</li> </ul> <p>It's live and free. I'd love feedback from this crowd specifically — on the architecture choices, on tools that break, or on what client-side tool you wish existed.</p> <p><strong>What would you have built differently?</strong></p> webdev showdev astro javascript