Finding Which Process is Locking a Port on macOS

How to find and kill a process using a specific port.

April 07, 2020 | Mike Buss

Occasionally, a process on my computer will open a port and refuse to release it. Here’s how to find the process and kill it.

lsof -i tcp:PORTNUMBER

For example, if I have a Rails server running in the background, I can run:

lsof -i tcp:3000 

To find the Rails process and its PID. To kill that process, I can then run:


Or, to combine searching for the process and killing it into one command:

kill -9 $(lsof -ti tcp:PORTNUMBER)

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About the Author

Mike Buss is a software engineer from Ohio who works primarily in the healthcare space. His work has been featured on and helped hundreds of thousands of patients. In his spare time, he writes about software development and more.

Follow @michaeltbuss on Twitter as he continues to document his software development journey.