JSON Formatter & Validator

Format, validate, and beautify JSON data online. Free JSON formatter with syntax highlighting, error detection, and minify option.

Last updated: June 1, 2026

Indent:

Input JSON

Output

What is JSON Formatter?

A JSON formatter is a developer tool that takes raw, minified, or poorly indented JSON (JavaScript Object Notation) data and reformats it with proper indentation, line breaks, and structure. JSON is the most common data format used in web APIs, configuration files, and data exchange between services. When JSON is minified (all whitespace removed) for transmission efficiency, it becomes nearly impossible to read. A JSON formatter restores readability, making it easy to understand data structures, find specific values, debug API responses, and validate that JSON syntax is correct.

How It Works

Paste or type JSON into the input area. The tool parses the input using a standards-compliant JSON parser, which validates the syntax simultaneously. If the JSON is valid, it's reformatted with consistent 2-space indentation, proper line breaks, and aligned brackets. If there are syntax errors — missing commas, unquoted keys, trailing commas, or mismatched brackets — the tool highlights exactly where the error occurs with a descriptive message. You can switch between beautified (expanded) and minified (compressed) output with one click. Everything runs locally in your browser.

Examples

Minified API response → Formatted

Input

{"name":"John","age":30,"address":{"city":"NYC","zip":"10001"},"hobbies":["reading","coding"]}

Output

{
  "name": "John",
  "age": 30,
  "address": {
    "city": "NYC",
    "zip": "10001"
  },
  "hobbies": [
    "reading",
    "coding"
  ]
}

Invalid JSON → Error detection

Input

{"name": "John", "age": 30,}

Output

Error: Trailing comma at position 27

Tips & Best Practices

💡

Use 2-space indentation for JSON — it's the most common standard and keeps nested structures readable without excessive horizontal scrolling.

💡

JSON doesn't support comments. If you need annotated configuration, consider YAML or JSON5 instead.

💡

Trailing commas are the most common JSON error. They're valid in JavaScript but not in JSON.

Common Use Cases

•Debugging API responses by making deeply nested JSON readable and navigable
•Validating JSON configuration files before deploying to production environments
•Formatting webhook payloads to understand the data structure being received
•Preparing JSON data for documentation, README files, and technical specifications
•Converting minified JSON from network requests into human-readable format for code review
•Validating JSON syntax before importing data into databases or ETL pipelines

Frequently Asked Questions

What does this JSON formatter do?▼

It takes raw or minified JSON and formats it with proper indentation, validates the structure, highlights syntax errors with line numbers, and makes it easy to read. You can also minify formatted JSON to save space.

Can I minify JSON too?▼

Yes, you can switch between formatted (beautified) and minified output with one click. Minification removes all unnecessary whitespace, reducing file size for production use.

Is my data safe?▼

All processing happens in your browser. No data is sent to any server. Your JSON never leaves your device, making it safe for sensitive configuration data, API keys in test payloads, and proprietary data structures.

What JSON errors does it detect?▼

The validator catches missing or extra commas, unquoted keys, single quotes instead of double quotes, trailing commas, mismatched brackets and braces, invalid escape sequences, and duplicate keys.

Does it support large JSON files?▼

Yes, the tool handles JSON files up to several megabytes. Performance depends on your browser and device, but most JSON payloads process instantly.

What indentation does it use?▼

The formatter uses 2-space indentation by default, which is the most common standard for JSON. The output is consistent and matches what most code editors and linters expect.