Find processes occupying a given port

lsofi

Rationale

• lsof -i :<port> for unix, darwin and win32 alike

Installation

npm install --save lsofi

Usage

ESM

import lsofi from 'lsofi'

const occupied = await lsofi(1337)
const free = await lsofi(1338)

console.log(occupied, free)
// => 9834 null

CommonJS

const lsofi = require('lsofi')

const occupied = await lsofi(1337)
const free = await lsofi(1338)

console.log(occupied, free)
// => 9834 null

Migration Notes

• Minimum supported Node.js version is now 20.0.0.
• Package now ships dual entry points using exports:
  • import lsofi from 'lsofi' (ESM)
  • require('lsofi') (CommonJS compatibility)
• Runtime dependencies removed:
  • is-number: replaced with native Number() and Number.isFinite() validation.
  • through2: replaced with native stream parsing via readline.

See also

• krampus - Kill processes occupying a given port

lsofi is built by marionebl and contributors. It is released under the MIT license.