Localhost Killer — Kill Any Process Using a localhost Port on Windows (VS Code Extension + Desktop App)

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Stop fighting with EADDRINUSE: address already in use. Find and kill any process listening on localhost:3000, :5173, :8080 — or any other port — with one click. Open-source, MIT-licensed, works without admin rights.

Localhost Killer is a free, open-source tool that lists every TCP port bound to 127.0.0.1, 0.0.0.0, ::1, or :: on your Windows machine, shows you which process owns each port (PID, executable name, command line), and lets you terminate them — individually or all at once — without ever touching netstat -ano and taskkill /F /PID again.

Ships in two flavors from the same codebase:

1. VS Code Extension — a sidebar view and status bar indicator inside your editor.
2. Windows Desktop App (Electron) — a standalone window with a system-tray icon for when you are not in VS Code.

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Common Errors This Tool Fixes

If you have ever seen any of these errors, this tool was built for you:

Error: listen EADDRINUSE: address already in use :::3000
Error: listen EADDRINUSE: address already in use 127.0.0.1:5173
Error: bind() to 0.0.0.0:8080 failed (10048: An attempt was made to access a socket...)
OSError: [Errno 98] Address already in use
java.net.BindException: Address already in use: bind
The process cannot access the file because it is being used by another process.
Failed to bind to address http://127.0.0.1:5000: address already in use.
Port 4200 is already in use. Use '--port' to specify a different port.
Something is already running on port 3000.
listen tcp 127.0.0.1:9090: bind: Only one usage of each socket address is normally permitted.

Common offenders Localhost Killer catches:

Stack	Default Port
Create React App / Next.js / Express	3000
Vite / SvelteKit	5173
Vue CLI	8080
Angular CLI	4200
Flask / Django dev	5000, 8000
Spring Boot	8080
ASP.NET Core	5000, 5001
Rails	3000
Storybook	6006
Webpack Dev Server	8080
Metro (React Native)	8081
json-server	3001
Docker Desktop forwards	varies
MongoDB / Postgres / Redis (local dev)	27017 / 5432 / 6379

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Features

• Scans every TCP listener on 127.0.0.1, 0.0.0.0, ::1, :: via netstat -ano and Get-CimInstance Win32_Process — no external dependencies.
• One-click kill per port, or Kill All to terminate every dev server at once.
• System-process protection: PID 0/4 and svchost.exe, lsass.exe, services.exe, wininit.exe, csrss.exe, smss.exe, winlogon.exe, spoolsv.exe, dwm.exe are flagged as protected and require explicit confirmation.
• Process-tree kill (taskkill /F /T) properly cleans up child workers, not just the parent.
• System tray support in the desktop app: minimize to tray, right-click for Kill All.
• VS Code status bar indicator shows the current count of listening localhost ports. Click it to open the view.
• Auto-refresh every 5 seconds, toggleable in both UIs.
• Click a port to open http://localhost:PORT in your default browser.
• Search by port, PID, process name, or command line.
• Dark and light themes auto-detected from the system.

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Quickstart

Install the VS Code Extension

git clone https://github.com/system-conf/localhostkiller.git
cd localhostkiller
npm install
npm run build:core
npm run package:vscode      # produces packages/vscode-extension/*.vsix
code --install-extension packages/vscode-extension/localhostkiller-vscode-*.vsix

Or load it as a development extension: open packages/vscode-extension/ in VS Code and press F5.

Install the Windows Desktop App

git clone https://github.com/system-conf/localhostkiller.git
cd localhostkiller
npm install
npm run build:core
npm run package:app         # produces packages/windows-app/release/*.exe

Two installers are produced:

• Localhost Killer-X.Y.Z-x64.exe — NSIS installer with Start Menu and desktop shortcuts.
• Localhost Killer-X.Y.Z-portable.exe — a single portable EXE, no install required.

The first release is unsigned. Windows SmartScreen will show "Windows protected your PC" — click "More info" then "Run anyway". Code-signing will land once a certificate is available.

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How It Works

Detection on Windows

1. Run `netstat -ano -p TCP` and parse LISTENING rows.
2. Filter local address to 127.0.0.1, 0.0.0.0, ::1, or ::.
3. Batch-fetch PID metadata via PowerShell:
     Get-CimInstance Win32_Process -Filter "ProcessId=X or ProcessId=Y ..."
4. Map PID to { Name, CommandLine, ExecutablePath }.
5. Tag known system PIDs as protected.

Kill

Windows:  taskkill /F /T /PID <pid>     # tree-kill (parent + children)
Linux:    process.kill(pid, 'SIGKILL')
macOS:    process.kill(pid, 'SIGKILL')  # uses lsof for detection

All logic lives in packages/core and is shared 1:1 between the VS Code extension and the desktop app.

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Architecture

This is a monorepo using npm workspaces:

localhostkiller/
├── packages/
│   ├── core/              # @localhostkiller/core — pure TS scanner + killer (no UI deps)
│   ├── vscode-extension/  # VS Code extension (TreeView + commands + status bar)
│   └── windows-app/       # Electron + React desktop app + system tray
├── .github/workflows/     # CI (build/lint) + Release (auto-publish .vsix + .exe)
└── LICENSE                # MIT

The @localhostkiller/core package exposes three async functions:

import { scanLocalhost, killPid, killAll } from '@localhostkiller/core';

const processes = await scanLocalhost();
// [{ pid: 12345, port: 3000, name: 'node.exe', cmdline: 'node server.js', protected: false, ... }]

await killPid(12345);

const result = await killAll({ includeProtected: false });
// { killed: [12345, 67890], failed: [] }

Use it directly from any Node.js script or Electron app — it is a regular npm package.

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Comparison with Alternatives

Tool	Platform	UI	Tree-kill	System-process guard	Open Source
Localhost Killer	Win/macOS/Linux	VS Code + Desktop	Yes	Yes	Yes (MIT)
netstat -ano + taskkill	Windows	CLI only	manual	No	n/a
kill-port (npm)	cross-platform	CLI only	partial	No	Yes
npx fkill	cross-platform	CLI / interactive	No	No	Yes
TCPView (Sysinternals)	Windows	GUI	No	No	No (closed)
Resource Monitor	Windows	GUI	No	No	No (built-in)

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Development

npm install
npm run build:core              # compile shared core first

npm run dev:vscode              # esbuild --watch, press F5 to launch
npm run dev:app                 # Vite + tsc --watch + Electron, hot reload UI

Project layout, scripts, and the IPC contract between the Electron main and renderer are documented in each package's README:

• packages/core/
• packages/vscode-extension/README.md
• packages/windows-app/README.md

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Contributing

Pull requests are welcome — see CONTRIBUTING.md. The shared scanner and killer logic is intentionally tiny (~250 lines) so it is easy to read end-to-end. Most contributions are likely to land in:

• Better process-metadata extraction (CWD, parent PID, port to URL guess).
• macOS and Linux UIs (the core already supports them via lsof and ss).
• A CLI wrapper around @localhostkiller/core for shell scripts.
• Better filtering and grouping in the UIs.

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FAQ

Does this need admin rights? No. taskkill /F works on any process you own. System-level services (which require admin) are filtered as protected by default.

Will it kill VS Code or my browser? No. The default behavior only lists processes that are listening on a localhost port. VS Code's renderer and your browser are not listening — they are connecting outward.

Can I use just the scanner library? Yes. npm i @localhostkiller/core and call scanLocalhost(). It returns a LocalhostProcess[].

Why TCP only? What about UDP? Dev servers are virtually always TCP. UDP support is a possible future addition — open an issue if you need it.

macOS or Linux support? The core works (lsof and ss), and the VS Code extension also works there with zero changes since it is pure Node. The standalone desktop app is currently Windows-only by build target — flip electron-builder.yml to add mac and linux targets if you want it.

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Keywords

kill localhost port · kill process on port windows · taskkill port · netstat kill port · EADDRINUSE · address already in use · port already in use · kill node process windows · kill dev server · vscode kill port extension · localhost port killer · free port windows · find process using port · windows port management · dev server killer · port 3000 in use · port 5173 in use · vite port killer · next.js port · react dev server port · npm run dev port · EADDRINUSE windows fix

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License

MIT © 2026 localhostkiller contributors

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