How to Pretty Print JSON in JavaScript, Python, Go and the Command Line

October 30, 2026 · 4 min read

To pretty print JSON, parse it and serialize it again with indentation: JSON.stringify(obj, null, 2) in JavaScript, json.dumps(obj, indent=2) in Python, json.MarshalIndent(v, "", " ") in Go, and jq . or python3 -m json.tool on the command line. For a one-off paste, the JSON formatter does the same in your browser without uploading anything.

Quick reference

JavaScript and Node.js

const data = { name: "Ada", langs: ["en", "fr"], active: true };

JSON.stringify(data, null, 2);    // 2 spaces
JSON.stringify(data, null, "\t"); // tabs

// Pretty print a JSON string you received
const pretty = JSON.stringify(JSON.parse(text), null, 2);

// Sorted keys (recursive)
const sortKeys = (v) =>
  Array.isArray(v) ? v.map(sortKeys)
  : v && typeof v === "object"
    ? Object.fromEntries(Object.keys(v).sort().map((k) => [k, sortKeys(v[k])]))
    : v;
JSON.stringify(sortKeys(data), null, 2);

The third argument accepts a number (capped at 10 spaces) or a string. In the browser console, console.log(obj) already shows an expandable tree; console.log(JSON.stringify(obj, null, 2)) gives copyable text. In Node, console.dir(obj, { depth: null }) prints nested objects fully instead of [Object].

JSON.parse converts numbers to doubles, so integers above 2^53 (9007199254740992) are rounded when you reformat this way. A formatter that preserves the original digits, like the JSON formatter here, avoids changing large IDs.

Python

import json

data = {"name": "Zoë", "langs": ["en", "fr"], "active": True}

print(json.dumps(data, indent=2))
print(json.dumps(data, indent=2, sort_keys=True))
print(json.dumps(data, indent=2, ensure_ascii=False))  # keep "Zoë" instead of "Zo\u00eb"

# Write a pretty file
with open("out.json", "w", encoding="utf-8") as f:
    json.dump(data, f, indent=2, ensure_ascii=False)
    f.write("\n")

pprint.pprint prints Python repr (single quotes, True), which is not valid JSON; use json.dumps when you need JSON output. Python keeps large integers exact, unlike JavaScript.

Go

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"os"
)

func main() {
	v := map[string]any{"name": "Ada", "langs": []string{"en", "fr"}}

	out, _ := json.MarshalIndent(v, "", "  ")
	fmt.Println(string(out))

	// Re-indent raw JSON bytes without decoding into a struct
	raw := []byte(`{"b":1,"a":[1,2]}`)
	var buf bytes.Buffer
	if err := json.Indent(&buf, raw, "", "  "); err != nil {
		fmt.Fprintln(os.Stderr, err)
	}
	fmt.Println(buf.String())
}

encoding/json writes map keys in sorted order, while struct fields keep their declaration order. json.Indent keeps the original key order and number text, which makes it the safest choice for reformatting JSON you did not produce. It also escapes <, > and & by default when marshaling; use an Encoder with SetEscapeHTML(false) if that bothers you.

Command line

# jq: pretty, colored in a terminal
jq . data.json
curl -s https://api.github.com/repos/jqlang/jq | jq .

jq --indent 4 . data.json   # 4 spaces
jq --tab . data.json        # tabs
jq -S . data.json           # sort keys
jq -c . data.json           # minify to one line

# No jq installed? Python ships with a formatter
python3 -m json.tool data.json
python3 -m json.tool --sort-keys --indent 4 data.json

# Reformat a file in place (write to a temp file first)
jq . data.json > tmp.json && mv tmp.json data.json

Never redirect into the file you are reading (jq . f.json > f.json): the shell truncates it before jq reads it and you lose the data. For very large files, jq's --stream mode or a viewer built for size is more practical; see how to open huge JSON files.

Editors

• VS Code: open a .json file and run Format Document (Shift+Alt+F on Windows, Shift+Option+F on macOS, Ctrl+Shift+I on Linux).
• JetBrains IDEs: Reformat Code (Ctrl+Alt+L, or Option+Command+L on macOS).
• Vim: :%!jq . pipes the buffer through jq.

When it fails to format

Every method above parses first, so invalid JSON stops with an error such as Unexpected token or Expecting property name enclosed in double quotes. Common causes are trailing commas, single quotes and comments; the common JSON errors guide explains each one, and the JSON fixer repairs them with a reviewable diff.