I Built an Invoice Generator in Pure HTML/CSS/JS — Here's Why

Hey devs! I'm VAIBHAV, a self-taught developer from Greater Noida, India. After paying ₹1,200/month for invoicing software I barely used, I decided to build my own. What I Built A fully client-side invoice generator that: Calculates GST automatically Generates PDFs with one click Works completely offline Stores data locally (privacy first) Runs on any device with a browser The Stack HTML5 CSS3 (no frameworks) Vanilla JavaScript html2pdf.js for PDF export No React. No Node. No backend. Just a single HTML file that works everywhere. Why This Matters Most invoicing tools charge monthly subscriptions. For freelancers in India, that adds up. I launched it on Gumroad for ₹1,250 one-time. Try it: [your Netlify link] Buy it: [your Gumroad link] First 10 buyers get 50% off with code EARLY50. The Code The entire product is a single HTML file. Here's the core logic: javascript // Auto-calculate totals function updateTotals() { const subtotal = items.reduce((sum, item) => sum + (item.qty * item.price), 0); const tax = subtotal * (taxRate / 100); const total = subtotal + tax; // Updates the invoice preview in real-time }