How to Kill a Process Running on a Specific Port

The Quick Way: One Command

With portrm, killing a process on any port takes one command:

$ ptrm fix 3000

  Port 3000 in use
  Node.js (PID 7821) - Express server
  SAFE - dev server, safe to kill

  Fix port 3000? [Y/n] Y
  Killed PID 7821 (SIGTERM)
  Port 3000 is now free

Skip confirmation: ptrm fix 3000 -y

Kill and restart: ptrm fix 3000 --run "npm start"

Kill multiple ports: ptrm fix 3000 8080 5432 -y

Install: npm install -g portrm or brew install abhishekayu/tap/portrm

macOS: Find and Kill Process on Port

Find what is using a port

$ lsof -i :3000
COMMAND  PID    USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
node    7821   user   23u  IPv6 0x...  0t0      TCP *:3000 (LISTEN)

Or get just the PID:

$ lsof -ti :3000
7821

Kill the process

$ kill -9 $(lsof -ti :3000)

Or step by step:

$ kill 7821       # graceful (SIGTERM)
$ kill -9 7821    # force (SIGKILL) if SIGTERM fails

Linux: Find and Kill Process on Port

Using lsof

$ lsof -i :3000
$ kill -9 $(lsof -ti :3000)

Using fuser

$ fuser 3000/tcp           # shows PID
$ fuser -k 3000/tcp        # kills it

Using ss + kill

$ ss -tlnp | grep :3000
LISTEN  0  511  *:3000  *:*  users:(("node",pid=7821,fd=23))
$ kill -9 7821

Windows: Find and Kill Process on Port

> netstat -ano | findstr :3000
  TCP    0.0.0.0:3000    0.0.0.0:0    LISTENING    7821

> taskkill /PID 7821 /F

PowerShell alternative:

> Get-NetTCPConnection -LocalPort 3000 | Select-Object OwningProcess
> Stop-Process -Id 7821 -Force

Common Ports and What Uses Them

Why Safe Kill Matters

Blindly running kill -9 is dangerous. It sends SIGKILL which:

• Does not allow the process to clean up resources
• Can cause data corruption in databases (PostgreSQL, MongoDB, Redis)
• May leave socket files and lock files behind
• Can orphan child processes

portrm solves this with a 3-tier safety system:

• BLOCKED: System processes (kernel, init, systemd) cannot be killed
• WARNING: Databases and data stores show a warning with data loss risk
• SAFE: Dev servers and build tools are approved for safe termination