This content originally appeared on DEV Community and was authored by Adeyomi Lawal
The Problem
Every developer has seen this error:
\
Error: Port 3000 is already in use
\\
And every developer has done this:
- Open Google
- Search "how to kill port process [your OS]"
- Copy-paste:
lsof -ti :3000 | xargs kill -9(macOS) - Hope it works
- Repeat tomorrow
After doing this 100+ times, I decided to build a solution.
Introducing zkill
zkill is a cross-platform CLI tool that kills zombie processes in one command:
\bash
zkill 3000
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That's it. Works on Mac, Linux, and Windows.
Features
- 🎯 Smart detection - Shows what process is using the port
- 🔒 Safe mode - Asks for confirmation before killing
- 🧠 Project-aware - Remembers which ports belong to which projects
- ⚡ Fast - Less than 100ms to detect processes
- 🎨 Beautiful CLI - Color-coded output with spinners
Installation
\bash
npm install -g zombie-port-killer
\\
Quick Start
\`bash
Kill process on port 3000
zkill 3000
Kill without confirmation
zkill 3000 --force
List all active ports
zkill scan
Show system info
zkill info
`\
Technical Deep Dive
Architecture
I built zkill using a cross-platform adapter pattern. Each OS has its own adapter:
-
macOS: Uses
lsofandps -
Linux: Uses
ss(ornetstatfallback) andps -
Windows: Uses
netstatandtasklist/taskkill
[Code snippet of adapter pattern]
TypeScript Setup
Built entirely in TypeScript for type safety and better DX:
\json
{
"compilerOptions": {
"target": "ES2020",
"module": "commonjs",
"strict": true,
// ...
}
}
\\
Testing
114 tests covering all major functionality:
- Unit tests for services
- Integration tests for commands
- Cross-platform compatibility tests
\bash
npm test
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What I Learned
1. Cross-Platform is Hard
Different operating systems use completely different commands for process management. Windows was particularly challenging.
2. UX Matters in CLI Tools
Even in a terminal, UX matters:
- Color-coded output
- Loading spinners
- Clear error messages
- Helpful prompts
3. Testing Saves Time
Comprehensive tests caught platform-specific bugs early and gave me confidence to ship.
4. Documentation is Critical
A good README is the difference between 0 users and 1000 users.
Roadmap
Coming in v1.1:
- Kill multiple ports:
zkill 3000 8000 5432 - Kill by process name:
zkill --name node - Port range support:
zkill --range 3000-3010
Try it Out!
\bash
npm install -g zombie-port-killer
zkill --help
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Links:
What do you think? What features would you like to see next?
If you found this useful, please star the repo and share it with other developers!
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This content originally appeared on DEV Community and was authored by Adeyomi Lawal
Adeyomi Lawal | Sciencx (2025-10-29T13:38:20+00:00) Building a Cross-Platform CLI Tool with TypeScript. Retrieved from https://www.scien.cx/2025/10/29/building-a-cross-platform-cli-tool-with-typescript/
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