Kak Fit

Overview

Kak Fit is a mobile-first workout tracker focused on logging and progress rather than social features. The mobile app is built with React Native, Expo Router, and TypeScript with light/dark themes; it talks to a Next.js + tRPC backend over a typed API, backed by PostgreSQL (via Supabase) and Prisma. Auth runs through Better Auth with Google OAuth and bearer tokens for mobile sessions. The exercise library is seeded from the Wger API (855 exercises), and nutrition tracking pulls from USDA FoodData Central for food search and macro tracking. The project is organized as a pnpm monorepo with a web (API) app, a mobile (Expo) app, and shared db/api packages.

Architecture

1. 01Monorepo: apps/web (Next.js API server) and apps/mobile (Expo React Native) share packages/db (Prisma schema + import scripts) and packages/api (tRPC routers).
2. 02Mobile client authenticates via Better Auth (Google OAuth), holding a bearer token for tRPC calls to apps/web.
3. 03apps/web exposes /api/trpc for the mobile client and /api/auth for session management, backed by Prisma over Supabase Postgres.

What I learned

• Sharing a typed tRPC API cleanly between a Next.js web backend and an Expo/React Native client.
• Structuring a pnpm monorepo with shared db and api packages across mobile and web apps.