Common Development Ports: 3000, 5000, 8000, 8080, 8888

Development Server Ports

Development frameworks use specific default ports. Knowing these helps avoid port conflicts and configure proxy settings.

Common Framework Defaults

Port	Framework / Tool
3000	React (Create React App), Next.js, Express.js, Grafana
3001	React (secondary), Storybook
4200	Angular CLI
4321	Astro
5000	Flask, .NET, Vite (older versions)
5173	Vite (current default)
5500	Live Server (VS Code)
8000	Django, PHP built-in server, Hugo
8080	Vue CLI, Spring Boot, Webpack Dev Server
8443	Spring Boot (HTTPS)
8888	Jupyter Notebook
9000	PHP-FPM, SonarQube

Handling Port Conflicts

When a port is already in use, most frameworks will suggest an alternative. You can also:

# Check what is using a port (Linux/macOS)
lsof -i :3000

# Check what is using a port (Windows)
netstat -ano | findstr :3000

# Kill process using a specific port (macOS/Linux)
kill -9 $(lsof -ti :3000)

Environment-Specific Port Configuration

Most frameworks support custom ports via environment variables or CLI flags:

# React
PORT=3001 npm start

# Next.js
next dev -p 4000

# Django
python manage.py runserver 0.0.0.0:9000

# Flask
flask run --port 5001