How to Find What Is Using a Port on Mac

Seeing EADDRINUSE or “port already in use”? Something on your Mac is already listening on that port. Here is how to find out what.

The quick answer: lsof

lsof -nP -iTCP:3000 -sTCP:LISTEN

Example output:

COMMAND   PID   USER   FD   TYPE   NODE NAME
node    18432  mohit   23u  IPv4    TCP 127.0.0.1:3000 (LISTEN)

The COMMAND and PID columns identify the process. The flags: -n and -P skip slow DNS and service-name lookups, -iTCP:3000 selects TCP port 3000, and -sTCP:LISTEN keeps only listeners.

The short form lsof -i :3000 also works, but it includes outgoing connections to that port too, which can be confusing.

Processes owned by other users

lsof only shows what your user may inspect. For system services use sudo:

sudo lsof -nP -iTCP:80 -sTCP:LISTEN

List every listening port

lsof -nP -iTCP -sTCP:LISTEN

Alternative: netstat

netstat -anv -p tcp | grep LISTEN | grep 3000

This shows the PID in its own column but is harder to read, and macOS’s netstat has no -p process option like Linux.

UDP

lsof -nP -iUDP:5353

The problem with the Terminal workflow

You have to remember the flags, switch windows, read columns, then run a second command to stop the process. Every time.

Faster: PortPeek

PortPeek shows every listening port in your menu bar. Type 3000 and you see the process and PID instantly. Next step: kill the process.