I’m ready to launch a lean, cross-platform billing site that supports both subscription plans and one-time purchases. The core requirement is rock-solid invoice generation: each transaction—whether recurring or single—must instantly produce a professional PDF (or similar) that customers can view, download, and receive by email. The build needs to function flawlessly in any modern browser while feeling perfectly at home on mobile screens. A single responsive code-base, a progressive web app, or another lightweight approach is fine as long as the UX is consistent. I’ll supply brand assets and hosting access. You’ll deliver: • A secure user-auth layer for customers and admins • An admin interface where I can create products, set subscription cycles, and review issued invoices • The invoice engine itself, complete with templating so I can tweak wording or add a logo • Deployment to my server and concise hand-off docs so I can manage basic edits without touching the code Future iterations may add payment-gateway integration or automated reminders, so laying a clean, modular foundation now is important. If you’ve built billing platforms before, especially those blending subscription logic with one-off sales, I’d love to see a demo or code sample. Let’s get this shipped.