JSON Formatter Online

What is a JSON Formatter?

Why Use an Online JSON Formatter

From debugging API responses to reviewing config files, a JSON formatter is one of the most-reached-for tools in a developer's daily workflow. You can format JSON using our tool above, then copy or download the result. Need the reverse? Use our free JSON minifier tool to compress formatted JSON back into a single line. You can also browse JSON examples by use case to see common patterns before writing your own.

How to Format JSON Online

Formatting happens in three stages — parse, transform, serialize.

JSON Formatter vs Validator vs Viewer

These three tools are related but serve distinct purposes. Here's when to reach for the validate JSON online tool or the free JSON Viewer tool instead of this formatter:

JSON Beautifier vs Minifier

Both tools transform JSON — but in opposite directions. Knowing when to use each one will save you debugging time and reduce API overhead.

Rule of thumb: beautify when you're reading JSON, minify when you're sending it. Use the online JSON minifier if you need to compress output after formatting.

Common JSON Errors

These are the most frequent causes of invalid JSON. Each invalid JSON example below includes the exact error and the corrected version. Paste your broken JSON into the formatter above — it will highlight the error location. For a dedicated error report with line numbers and a full guide, visit our JSON errors guide or try the JSON syntax checker. Note: these tools check syntax validity only — for JSON schema validation (type-level checking against a schema definition), you need a dedicated JSON Schema validator.

JSON Formatting Examples

{"user":{"id":1,"name":"Alice","role":"admin","active":true}}

{
  "user": {
    "id": 1,
    "name": "Alice",
    "role": "admin",
    "active": true
  }
}

[{"id":1,"name":"Alice"},{"id":2,"name":"Bob"},{"id":3,"name":"Charlie"}]

[
  { "id": 1, "name": "Alice" },
  { "id": 2, "name": "Bob" },
  { "id": 3, "name": "Charlie" }
]

{"status":"success","data":{"token":"eyJhbGc...","expires_in":3600},"meta":{"request_id":"abc123","timestamp":1704067200}}

{
  "status": "success",
  "data": {
    "token": "eyJhbGc...",
    "expires_in": 3600
  },
  "meta": {
    "request_id": "abc123",
    "timestamp": 1704067200
  }
}

API Debugging Guide

When an API request fails or returns unexpected data, a JSON formatter is the fastest way to understand what went wrong. Here's a repeatable debugging workflow:

Frequently Asked Questions

Related JSON Tools

Every JSON workflow is different. Use these tools alongside the formatter to validate, explore, shrink, and convert your data.

Format JSON from the Terminal

Need to format JSON without leaving your terminal? Here are the fastest one-liners for every platform — no extra tools required for Python and Node.js. For piping API responses, jq is the standard choice.

How to Format JSON in Your Language

Every major language has a built-in JSON library. Here are the exact functions to pretty-print JSON with consistent indentation — no third-party package needed.

// Format a JSON string
const formatted = JSON.stringify(JSON.parse(raw), null, 2);

// Format an existing object
const formatted = JSON.stringify(myObject, null, 2);

// Write formatted JSON to a file (Node.js)
const fs = require('fs');
fs.writeFileSync('out.json', JSON.stringify(data, null, 2));

import json

# Format a JSON string
formatted = json.dumps(json.loads(raw_str), indent=2)

# Format a Python dict
formatted = json.dumps(my_dict, indent=2)

# Read, format, and write a JSON file
with open('data.json') as f:
    data = json.load(f)
print(json.dumps(data, indent=2))

import (
    "encoding/json"
    "bytes"
)

// Indent a JSON []byte
var out bytes.Buffer
json.Indent(&out, rawJSON, "", "  ")
fmt.Println(out.String())

// Marshal with indentation
b, _ := json.MarshalIndent(myStruct, "", "  ")

// Using Jackson
ObjectMapper mapper = new ObjectMapper();
mapper.enable(SerializationFeature.INDENT_OUTPUT);
String formatted = mapper.writeValueAsString(myObject);

// Parse and re-format a JSON string
Object obj = mapper.readValue(rawJson, Object.class);
String pretty = mapper.writerWithDefaultPrettyPrinter()
                       .writeValueAsString(obj);

// Format a JSON string
$formatted = json_encode(
    json_decode($rawJson),
    JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE
);

// Format and save to file
file_put_contents('out.json', json_encode(
    json_decode(file_get_contents('data.json')),
    JSON_PRETTY_PRINT
));

use serde_json::Value;

// Parse then pretty-print
let v: Value = serde_json::from_str(&raw_json)?;
let pretty = serde_json::to_string_pretty(&v)?;

// Pretty-print a struct
#[derive(Serialize)]
struct User { name: String }
let pretty = serde_json::to_string_pretty(&user)?;

JSON Syntax Cheat Sheet

A complete reference to valid JSON syntax — bookmark this when you need to verify what's allowed and what isn't. JSON is defined by RFC 8259.

{
  name: "Alice",          // key not quoted
  'role': 'admin',        // single quotes
  "score": NaN,           // NaN not allowed
  "tags": ["a", "b",],   // trailing comma
  // this is a comment   // no comments in JSON
}

{
  "name": "Alice",
  "role": "admin",
  "score": null,
  "tags": ["a", "b"],
  "active": true
}

JSON vs XML, YAML, CSV — Which Should You Use?

JSON is the dominant format for APIs and config files, but it's not always the right choice. Here's how it compares against the other formats you'll encounter in real projects.

Handling Large JSON Files

This formatter handles files up to ~50MB entirely in your browser. For larger files, different strategies apply depending on the source and target. Here's a decision framework used by data engineers and backend developers.

{"id":1,"event":"click"}
{"id":2,"event":"scroll"}
{"id":3,"event":"purchase"}

# Node.js: compress JSON response
res.setHeader("Content-Encoding", "gzip");
res.end(zlib.gzipSync(JSON.stringify(data)));

{
  "data": [...],
  "meta": {
    "next_cursor": "eyJpZCI6MTAwfQ==",
    "has_more": true
  }
}

const Ajv = require("ajv");
const ajv = new Ajv();
const valid = ajv.validate(schema, data);
if (!valid) console.log(ajv.errors);