Package Exports

jsonfmt-dev
jsonfmt-dev/index.js

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Readme

@jsonfmt/cli

Format, validate, diff, and inspect JSON from your terminal.

Zero dependencies. Colorized output. Runs anywhere Node.js runs.

Install

npm install -g @jsonfmt/cli

Or run instantly without installing:

npx @jsonfmt/cli '{"hello":"world"}'

Quick Start

# Format a file
jsonfmt data.json

# Pipe from stdin
echo '{"name":"Alice","age":30}' | jsonfmt

# Validate
jsonfmt --validate data.json

# Diff two files
jsonfmt --diff a.json b.json

# Get stats
jsonfmt --stats data.json

Output Example

$ echo '{"name":"Alice","age":30,"roles":["admin","user"],"active":true}' | jsonfmt

{
  "name": "Alice",
  "age": 30,
  "roles": [
    "admin",
    "user"
  ],
  "active": true
}

$ jsonfmt --stats data.json

  keys       3
  strings    1
  numbers    1
  booleans   1
  arrays     1
  objects    1
  depth      2
  bytes      65

$ jsonfmt --diff a.json b.json

  ~ age: 28 → 29
  + role: "admin"
  - email: "old@test.com"

All Options

Flag	Description	Example
(no flag)	Pretty-print with colors	`jsonfmt data.json`
`--minify`	Compact single-line output	`jsonfmt --minify data.json`
`--sort-keys`	Sort object keys A-Z	`jsonfmt --sort-keys data.json`
`--validate`	Check validity (exit 0/1)	`jsonfmt --validate data.json`
`--stats`	Count keys, types, depth, bytes	`jsonfmt --stats data.json`
`--diff <file>`	Compare two JSON files	`jsonfmt --diff a.json b.json`
`--get <path>`	Extract value by dot-path	`jsonfmt --get "users[0].name" data.json`
`--indent <n\|tab>`	Set indentation (default: 2)	`jsonfmt --indent 4 data.json`
`--max-depth <n>`	Truncate nested output	`jsonfmt --max-depth 3 data.json`
`--max-array <n>`	Truncate long arrays	`jsonfmt --max-array 5 data.json`
`--no-color`	Disable ANSI colors	`jsonfmt --no-color data.json > out.txt`
`--help`	Show help	`jsonfmt --help`

Use Cases

CI/CD pipelines — validate JSON configs before deploy:

jsonfmt --validate config.json || exit 1

API debugging — format curl responses:

curl -s https://api.example.com/users | jsonfmt

Extract values — pull fields from JSON files:

jsonfmt --get "database.host" config.json

Compare configs — diff staging vs production:

jsonfmt --diff staging.json production.json

Minify for storage — shrink JSON payloads:

jsonfmt --minify large.json > small.json

How It Works

Custom Lexer -> Parser -> AST pipeline (same engine as jsonfmt.dev):

Input string
  → Lexer (tokenize: strings, numbers, braces, colons)
  → Parser (build AST: objects, arrays, values)
  → Formatter (colorize + indent)
  → Terminal output

Better error messages than JSON.parse — shows exact line and column
Handles all JSON edge cases (unicode escapes, nested depth, large files)
Zero dependencies — single 25KB file, no node_modules

Ecosystem

Product	What	Link
Web App	Full JSON toolkit (33 converters, 8 tabs, AI Helper)	jsonfmt.dev
API	63 REST endpoints for JSON processing	api.jsonfmt.dev/docs
CLI	This package	`npm i -g @jsonfmt/cli`
Chrome Extension	Auto-format JSON in browser tabs	Chrome Web Store
Bookmarklet	One-click format on any page	jsonfmt.dev/bookmarklet

Why Not Just Use `jq`?

	`jsonfmt`	`jq`
Install	`npm i -g @jsonfmt/cli`	Separate binary, varies by OS
Syntax	Familiar flags (`--get`, `--diff`)	Custom query language to learn
Colors	Built-in, automatic	Requires `--color-output`
Diff	`--diff a.json b.json`	Not built-in
Validate	`--validate` with exit codes	`jq . > /dev/null` (workaround)
Stats	`--stats` (types, depth, bytes)	Not built-in
Deps	Zero	C binary

Use jsonfmt for formatting, validating, and inspecting. Use jq for complex data transformations.

License

MIT

jsonfmt.dev — Format, validate, convert, diff, repair, and query JSON.

jsonfmt-dev