Building a CLI Tool with Node.js: From Zero to npm

A step-by-step guide to building, testing, and publishing a command-line tool.

Why Build a CLI?

Solves YOUR problem (automate repetitive tasks)

Portfolio piece (shows you can ship complete tools)

Potential income (people pay for useful CLIs)

Fun to build (instant gratification — no UI needed)

What We'll Build

A jsonfmt tool that formats JSON files in place:

$ cat messy.json { "name" : "Alex" , "age" :30, "skills" :[ "js" , "python" ]}

$ jsonfmt messy.json

$ cat messy.json { "name" : "Alex" , "age" : 30, "skills" : [ "js" , "python" ] }

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Step 1: Project Setup

mkdir jsonfmt && cd jsonfmt npm init -y

# Install dependencies npm install commander chalk fs-extra

# Install dev dependencies npm install -D jest typescript @types/node tsup

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// package.json { "name" : "jsonfmt" , "version" : "1.0.0" , "description" : "Format JSON files beautifully" , "type" :…