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Port Management Guides

Step-by-step solutions for every port conflict, EADDRINUSE error, and process management task. Every guide covers macOS, Linux, and Windows.

Port conflicts are the most common blocker in local development. Whether you are running React on port 3000, Express on 8080, or a Docker container fighting for port 5432, the fix should take seconds, not minutes of Googling lsof flags.

These guides cover every scenario we have seen across thousands of developer setups. Each one includes the manual commands and the one-command portrm solution.

Fix Specific Errors

Start here if you just hit an error message and need the fix now.

Fix EADDRINUSE Error
The complete guide to Error: listen EADDRINUSE: address already in use. Covers Node.js, Express, Next.js, and all frameworks.
What is EADDRINUSE?
Deep dive into what EADDRINUSE means, why it happens, and how TCP port binding works under the hood.
Address Already in Use Error
Fix "address already in use" across all languages: Node.js, Python, Go, Java, Ruby, and .NET.
Port Already in Use (Node.js)
Node.js-specific solutions for Express, Next.js, Vite, and other frameworks that throw port conflicts.

Kill Processes on Ports

Need to free a specific port? These guides show you how on every operating system.

Kill Process on Any Port
Find and kill a process running on any port. Complete guide for macOS, Linux, and Windows.
Kill Port 3000 on Mac
Free port 3000 on macOS using lsof, kill, or portrm. Covers Apple Silicon and Intel Macs.
Kill Port 3000 on Windows
Free port 3000 on Windows using netstat, taskkill, PowerShell, or portrm CLI.
Kill Port 8080 on Linux
Free port 8080 on Ubuntu, Debian, Fedora, and other Linux distros with fuser, ss, and portrm.

Free Common Ports

Quick-fix guides for the ports developers fight over the most.

Free Port 3000
Port 3000 is the default for React, Next.js, and Express. Find what is using it and kill it safely.
Free Port 8080
Port 8080 is used by Spring Boot, Tomcat, Jenkins, and backend APIs. Free it on any OS.
Port 5000 in Use on Mac
macOS Monterey+ runs AirPlay Receiver on port 5000 by default. Here is how to fix it.
List All Ports in Use
See every listening port on your system with lsof, ss, netstat, or portrm scan.

Framework-Specific Fixes

Port conflict solutions tailored to your framework.

Node.js Port Conflict Fix
Comprehensive guide to resolving port conflicts in any Node.js application.
React Port 3000 in Use
Fix "Something is already running on port 3000" in Create React App and Vite React.
Next.js Port Already in Use
Fix port conflicts in Next.js dev server, including App Router and Pages Router setups.
Express Port in Use Fix
Handle EADDRINUSE in Express.js with graceful shutdown, SO_REUSEADDR, and portrm.
Vite Port Already in Use
Fix "Port 5173 is already in use" in Vite dev server for React, Vue, and Svelte projects.
Docker Port Conflict Fix
Resolve "port is already allocated" in Docker. Fix docker-compose port mappings and conflicts.

Diagnostic Tools

Learn how to inspect and manage ports on your system.

How to Find Process Using a Port
Use lsof, netstat, ss, and portrm to find which process is binding to any port on your machine.
portrm vs lsof
Why portrm gives you more than raw lsof output: service detection, safety tiers, memory, and uptime.
portrm vs kill-port
Feature-by-feature comparison between portrm and the kill-port npm package.
portrm vs fkill
Compare portrm to Sindre Sorhus fkill-cli for process management and port conflict resolution.

Skip the manual commands

portrm detects the service, checks if it is safe to kill, and frees the port in one command. 1.2 MB binary, zero dependencies.

Install portrm Read the docs →