I have an existing invoicing webapp that I use every day, but I need a private duplicate that I can host and control myself. Your task is to recreate its core functionality from scratch so that it runs smoothly in any modern browser and scales down gracefully to mobile devices as a progressive web app. The essentials are straightforward: the system must generate invoices automatically from saved templates and keep a tidy database of my clients, contacts, and billing history. I want the interface and workflow to feel just as snappy as the original; however, the underlying code, tech stack, and deployment pipeline are entirely up to you. If you prefer React, Vue, Angular, or another framework, that’s fine—just make sure it’s maintainable and well-documented so I can hand it over to future developers without headaches. Key deliverables • Fully responsive web & mobile experience (PWA is ideal) • Automated invoice creation with customizable templates and sequential numbering • Client management module with basic CRUD, search, and tagging • Simple, self-hosted database setup (PostgreSQL, MySQL, or another open-source DB you recommend) • Dockerized or otherwise scriptable deployment so I can spin it up on my own server with one command • Developer-level documentation: install steps, environment variables, and a short architecture overview Acceptance criteria 1. I can add a new client, create an invoice in under a minute, and export it to PDF. 2. The webapp works offline first and syncs when a connection returns. 3. Lighthouse mobile performance score ≥ 90. 4. Source code passes an automated lint/test suite that you include. Payment processing isn’t on the roadmap right now, but if you build with extensibility in mind, I may expand the scope later, which could mean more work for you. Let me know your preferred stack, a timeline, and any clarifying questions so we can get started. Bottom line. Your proposal will be auto deleted for spam if you do not include your favorite book in the first line of your proposal.