NetLink

A real-time chat application with web and mobile clients.

Tech Stack

• Backend: Go (stdlib net/http), PostgreSQL (pgx), Gorilla WebSocket
• Frontend: Next.js 16, React 19, Tailwind CSS v4, TypeScript
• Mobile: Expo SDK 54, React Native, Zustand, TypeScript
• Deployment: Docker (Railway), Vercel (frontend), EAS Build (mobile)

Features

• Real-time messaging via WebSocket (multi-device support)
• Direct and group conversations
• Message editing, deletion (soft delete), forwarding
• Emoji reactions (system + custom)
• Voice messages with waveform visualization
• Email verification and password reset (Gmail SMTP / Resend API)
• Session-based authentication (cookie + bearer token)
• Optimistic UI updates on web and mobile
• Rate limiting on auth endpoints

Project Structure

backend/          Go HTTP + WebSocket server
  auth/           Authentication service
  handlers/       HTTP request handlers
  middleware/     Rate limiter, JSON response helpers
  models/         Data models
  repository/     PostgreSQL queries (raw SQL, no ORM)
  services/       Email service (Gmail SMTP / Resend)
  websocket/      Hub + client (real-time event broadcasting)
frontend/         Next.js web app
mobile/           Expo React Native app

Getting Started

Prerequisites

• Go 1.25+
• PostgreSQL
• Node.js / Bun (for frontend)
• Expo CLI (for mobile)

Backend

cd backend
cp .env.example .env  # fill in DATABASE_URL, email config
go run main.go

Frontend

cd frontend
bun install
bun dev

Mobile

cd mobile
npm install
npx expo start

Environment Variables

Variable	Description
DATABASE_URL	PostgreSQL connection string
PORT	Server port (default: 8080)
ALLOWED_ORIGINS	Comma-separated CORS origins
ENV	Set to production for secure cookies
APP_URL	Base URL for email links
GMAIL_USERNAME	Gmail address for SMTP
GMAIL_APP_PASSWORD	Gmail app password
RESEND_API_KEY	Resend API key (alternative to Gmail)
FROM_EMAIL	Sender email address

Running Tests

cd backend
go test ./... -v

Known Limitations

• Voice files stored on local filesystem (should use S3/MinIO for production)
• No end-to-end or integration tests yet (unit tests only)
• HTML template routes (/login, /register) are legacy from early development