SMPLNVST Paper Trading App
Software Design and Development · 2026
SMPLNVST is a stock market trading simulation app that helps people learn the basics of investing and maintain a virtual portfolio using real-time market data.
The product focuses on presenting trading workflows and portfolio performance in a way that feels clear, understandable, and less intimidating than traditional trading platforms.
Throughout the experience, users are introduced to investing concepts and financial terminology in context, helping them build confidence as they develop long-term investing habits and explore different trading strategies.
I designed and built the entire software experience from the ground up to make virtual trading, portfolio tracking, and performance analysis feel approachable for beginners while still useful for more experienced investors testing strategies.
Every surface — the marketing landing page, the trading flows, modals, charts, and portfolio analytics — was designed and engineered as one cohesive system, anchored by a custom shared component library.
The codebase is structured as a TypeScript monorepo: a React + Tailwind web app and a React Native (Expo) mobile app share a common core package that owns the data hooks, API adapters, and investing calculations — cost-basis lot tracking, realized and unrealized gains, wash-sale detection, dividend and stock-split handling — so business logic stays consistent across platforms while each app still owns its native navigation, auth, and storage.
Live market data from Massive.com flows through a custom server-side adapter on Supabase Edge Functions (Postgres, row-level security, two-level caching) so the upstream API key stays off the client and data fetches amortize across users.
Both the web and mobile apps integrate with RevenueCat's subscription infrastructure.
Tech Stack
- Frontend: React 19 · TypeScript · Tailwind 4 · Vite · React Native + Expo · Recharts · TanStack Query · dnd-kit
- Backend: Supabase · Postgres · Edge Functions (Deno) · Row-Level Security · pg_cron
- Market data: Massive API · two-level server-side cache
- Subscription services: RevenueCat
- Infrastructure: Cloudflare Pages (static + SPA, _redirects-driven routing) · auto-deploy on push to remote main on Github
Web app - Portfolio summary
Web app - Stock ticker details
Web app - Sell shares
iOS app - Dashboard
iOS app - Ticker details & Trade screen
iOS app - Watch list & Transactions
iOS app - Notifications & Action menu
