The Node.js + Express API lives in the backend/ directory. It serves JSON under /api and stores temporary data in backend/data/ (ignored by git).

• Node.js 18+ (LTS recommended)
• npm (comes with Node)

From the repository root:

cd backend
npm install

Development (restarts the process when files change):

cd backend
npm run dev

Production-style (no file watcher):

cd backend
npm start

The API listens on http://localhost:4001 by default. Check health with http://localhost:4001/api/health.

Optional environment variables:

• PORT — override the listen port (default 4001).
• DATA_FILE — absolute path to the JSON file used for temp storage (default backend/data/data.json).

The library page calls Places API (New) on the backend. Copy backend/.env.example to backend/.env and set:

• GOOGLE_PLACES_API_KEY — create a key in Google Cloud Console, enable Places API (New), and (recommended) restrict the key to that API.

Optional:

• DEFAULT_MAP_LAT / DEFAULT_MAP_LNG — defaults for “nearby” when the user does not share location (preset: World Trade Center area).

Restart the backend after changing .env.

The Next.js app lives in the frontend/ directory.

• Node.js 18+ (LTS recommended)
• npm (comes with Node)

From the repository root:

cd frontend
npm install

cd frontend
npm run dev

Open http://localhost:3000 in your browser. The dev server reloads when you change files.

For the Libraries page, the frontend calls the Express API (by default http://localhost:4001). Copy frontend/.env.example to frontend/.env.local if you need a different base URL:

• NEXT_PUBLIC_API_BASE_URL — e.g. http://localhost:4001 (no trailing slash).

Run the backend and frontend together in development.

cd frontend
npm run build
npm start

npm start serves the optimized build (defaults to port 3000 unless PORT is set).