Built a production-grade WhatsApp bot platform from scratch: no prior codebase, just a blank folder. Here's what it does: → Users sign up & connect WhatsApp via QR scan → Set keyword-based auto-reply rules (CONTAINS, EXACT, REGEX, etc.) → Replies fire automatically with custom delay → Live message logs update in real time → SaaS tiers (Free → Business) with rule limits enforced Tech stack Claude Code wired up end-to-end: - Next.js 14 + TypeScript + Tailwind + shadcn/ui - NextAuth (login/signup) - SQLite + Prisma - Socket.io for real-time QR delivery & live logs - whatsapp-web.js (Puppeteer-based) What blew me away: Claude Code didn't just write code: it diagnosed bugs, fixed race conditions in the QR flow, rewrote the session manager singleton to survive hot-reloads, and even refactored the database layer mid-build when I switched from Postgres to SQLite. Zero backend experience needed. I just described what I wanted. If you're sleeping on Claude Code for building real products, you're leaving serious leverage on the table.