zport

Kill processes running on specified ports. Fast, zero-dependency, cross-platform.

Why zport?

Existing tools like kill-port shell out to lsof -i -P and parse the entire connection table with a loose regex — which means they miss processes, false-match adjacent port numbers, and fail silently on Linux when lsof isn't installed.

zport fixes all of that:

• Linux — uses fuser (fast, exact match) → falls back to ss → then lsof
• macOS — uses lsof -ti with exact port + LISTEN filter
• Windows — uses netstat -ano with exact port + LISTENING match → taskkill
• Zero dependencies — just Node.js child_process.execFile, no shell spawning
• TypeScript — fully typed, ships with declarations

Install

npm i -g zport

Or run directly without installing:

npx zport 3000
bunx zport 3000

Usage

CLI

# Kill a single port
zport 3000

# Kill multiple ports
zport 3000 3001 8080

# Comma-separated
zport 3000,3001,8080

# UDP instead of TCP
zport 5353 --method udp
zport 5353 -m udp

Output:

✔ :3000 — killed pid 12345
✔ :3001 — killed pids 12346, 12347
✘ :8080 — No process on this port

Programmatic

import { kill } from "zport";

const result = await kill(3000);
// { port: 3000, pids: [12345], killed: true }

const result2 = await kill(9999);
// { port: 9999, pids: [], killed: false, error: "No process on this port" }

kill(port, method?)

Param	Type	Default	Description
port	number	—	Port number (1–65535)
method	"tcp" | "udp"	"tcp"	Protocol to match

Returns Promise<KillResult>:

interface KillResult {
  port: number;
  pids: number[];
  killed: boolean;
  error?: string;
}

How it works

OS	Find PIDs	Kill
Linux	fuser {port}/tcp → ss -tlnp → lsof -ti	SIGKILL
macOS	lsof -iTCP:{port} -t -sTCP:LISTEN	SIGKILL
Windows	netstat -ano (exact port + LISTENING)	taskkill /F

On Linux, fuser is tried first because it directly queries the kernel's socket table — no parsing, no regex, no false matches. If fuser isn't available (minimal containers), it falls back to ss, then lsof.

License

MIT