Built a React SaaS dashboard for ops leads: KPI charts, filterable tables, saved views, and role-based menus (admin / analyst / viewer). Dark mode with tokenized theme; data from REST with cached queries and stale-while-revalidate. Empty/error/loading states on every widget. Stack: React, TypeScript, Recharts, React Router, TanStack Query. Replaced a slow spreadsheet ritual; first paint stayed usable on mid-range laptops. NDA: product name withheld.