JSON Formatter & Validator

What is JSON?

JSON Formatting and Validation

// Minified (compact for production)
{"name":"John","age":30,"skills":["JavaScript","Python"]}

// Formatted (readable for development)
{
  "name": "John",
  "age": 30,
  "skills": [
    "JavaScript",
    "Python"
  ]
}

Common JSON Syntax Errors

Working with JSON in Code

// JavaScript / Node.js
const obj = JSON.parse('{"name": "John"}');
const str = JSON.stringify(obj, null, 2); // pretty-print

// Python
import json
data = json.loads('{"name": "John"}')
formatted = json.dumps(data, indent=2)

// Command line (jq)
echo '{"name":"John"}' | jq '.'

Frequently Asked Questions

What's the difference between JSON and a JavaScript object?

JSON is a text format with strict syntax rules: double-quoted keys, no functions, no undefined, no trailing commas. JavaScript objects are in-memory data structures with looser syntax. JSON.parse() converts JSON text to a JS object, and JSON.stringify() does the reverse.

Why is my JSON invalid?

Common causes: trailing commas after the last property, single quotes instead of double quotes, unquoted property names, comments in the JSON, or control characters in strings. Paste your JSON in this tool to see the exact error location.

What's the maximum size of a JSON file?

JSON itself has no size limit. Practical limits depend on your parser and available memory. Most APIs limit request bodies to 1-10 MB. For large datasets, consider streaming parsers or formats like NDJSON (newline-delimited JSON).

Should I use JSON or YAML for configuration?

JSON is better for machine-to-machine data (APIs, storage). YAML is more human-friendly for config files due to comments and less syntax noise. Many tools support both. JSON is stricter, which means fewer ambiguity issues.

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