PORT 3000 / TCPDev & LocalhostExposure Risk: Low

Port 3000: Next.js / Node / React — Default Local Development Server (Next.js, Express, Grafana)

The most common development port used by Next.js, Create React App, Express.js, Ruby on Rails, and Grafana dashboards.

Default Service

Next.js / Node / React

Process: node / next-server

Transport Protocol

TCP

IANA Registered Port 3000

Docker Port Flag

-p 3000:3000

Container to Host Mapping

How to Check & Kill Process on Port 3000 (EADDRINUSE Fix)

macOS & Linux (lsof / kill)

# Find process using port 3000
sudo lsof -i :3000

# Instantly kill process on port 3000
lsof -ti:3000 | xargs kill -9

Windows (PowerShell & CMD)

# Find PID listening on port 3000
netstat -ano | findstr :3000

# Force kill by PID
taskkill /PID <PID_NUMBER> /F

Cross-Platform Node.js One-Liner

# Kill port 3000 via npx
npx kill-port 3000

# Or diagnose via Castov CLI
npx castov fix "EADDRINUSE :::3000"

Linux Firewall (UFW) & Connectivity Test

# Test if port 3000 is reachable
nc -zv localhost 3000

# Allow or deny port 3000 in UFW
sudo ufw allow 3000/tcp

Frequently Asked Questions about Port 3000

What is Port 3000 used for?

Port 3000 is the standard network port for Next.js / Node / React (Default Local Development Server (Next.js, Express, Grafana)) operating over TCP. The typical system daemon or process is node / next-server.

How do I kill a process running on Port 3000 (EADDRINUSE)?

On macOS and Linux, run: lsof -ti:3000 | xargs kill -9 (or npx kill-port 3000). On Windows PowerShell/CMD, run: netstat -ano | findstr :3000 and then taskkill /PID <PID> /F.

Is it safe to expose Port 3000 to the internet?

Port 3000 has a Low security risk profile. The most common development port used by Next.js, Create React App, Express.js, Ruby on Rails, and Grafana dashboards.