fkp — fast kill port

Kill processes listening on one or more ports. Cross-platform (macOS, Linux, Windows). Zero dependencies.

npx @ugurkellecioglu/fkp 3000
npx @ugurkellecioglu/fkp 3000 8080 5173
npx @ugurkellecioglu/fkp --tcp 3000    # leave clients alone, only kill the listener
npx @ugurkellecioglu/fkp --udp 53      # kill UDP bindings (DNS, game servers, etc.)

Why another kill-port tool?

Compared to the two popular alternatives:

• kp runs lsof -i:PORT | xargs killall, which matches by process name. kp 3000 will kill every node (or python, etc.) process on your machine, not just the one on port 3000. Single port only.
• kill-port targets PIDs correctly, but as an existence check it runs lsof -i -P — which enumerates every network socket on the system. On a busy dev box that alone takes multiple seconds before it even starts killing.

fkp does neither. It runs one targeted lsof -ti:<ports> and one kill -9 with all PIDs, no shell, no deps.

Flags

| Flag | Behavior | |---|---| | (none) | Fastest. Kills every process with a socket on the port(s) — listeners and any connected clients. | | --tcp | Only kills TCP listeners. Safe mode — won't touch processes (e.g. Chrome, curl, psql) that happen to have an open connection to the port. | | --udp | Only kills UDP sockets bound to the port. | | --tcp --udp | Union of both filtered queries. |

The default prioritizes speed. Pass --tcp when you want "kill the server, leave my client open" semantics.

Benchmark

macOS, 5 runs, wall-clock including Node startup:

| Scenario | fkp (default) | fkp --tcp | kp | kill-port | |---|---|---|---|---| | 1 port | 263 ms | 263 ms | 288 ms | 6495 ms | | 3 ports | 266 ms | 264 ms | ~480 ms (N invocations) | ~5700 ms |

fkp stays flat across port count — one lsof and one kill call regardless of how many ports. kp grows linearly (one Node startup per port). kill-port is bottlenecked on the system-wide lsof -i -P scan.

How it works

• macOS / Linux: lsof -ti:3000,8080,5173 → kill -9 <pids>. With --tcp: lsof -ti tcp:<ports> -sTCP:LISTEN. With --udp: lsof -ti udp:<ports>.
• Windows: one netstat -ano parse → taskkill /F /PID x /PID y /PID z. Flags filter the protocol/state in the parser.
• Uses execFile (no shell) for speed and safety.
• Exits 0 whether or not a process was found.

Install

npm i -g @ugurkellecioglu/fkp
# then
fkp 3000

# or one-off
npx @ugurkellecioglu/fkp 3000

License

MIT