#To list any process listening to the port 8080:
lsof -i:8080

#To kill any process listening to the port 8080:
kill $(lsof -t -i:8080)

#or more violently:
kill -9 $(lsof -t -i:8080)

sudo kill -9 `sudo lsof -t -i:9001`

npx kill-port 3000

kill -9 $(lsof -t -i:8080)

npx kill-port 8080

kill $(lsof -ti:3000)