I Built a Multi-Tenant Website Builder with One...

I spent the last few months building Zenpage, a free website builder for authors. One codebase serves both the dashboard (where authors build their sites) and every published author site - on subdomains and custom domains - using hostname-based routing in a single Next.js 15 deployment. This post breaks down the architecture decisions, the tricky parts, and what I'd do differently. The stack Runtime: Bun Framework: Next.js 15 App Router, React 19 Styling: Tailwind CSS v4, shadcn/ui API: tRPC wit