JSON Formatter & Validator

Format, validate, and analyze JSON data with indentation and structure info.

By Konstantin Iakovlev · Updated September 2026 · Source: RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format (IETF, 2017)

Status

Valid JSON

Keys

3

Formatted

{
  "name": "John",
  "age": 30,
  "skills": [
    "JS",
    "React"
  ]
}

JSON Stats

ValidYes
Total Keys3
Max Depth2
Size48 bytes

Use the JSON Formatter & Validator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only. Results are estimates based on the information you provide and the assumptions described on this page.

How It Works

A JSON Formatter & Validator ensures your JSON data is correctly structured and easily readable. It's crucial for developers and data analysts to prevent parsing errors and maintain data integrity, especially in APIs and configuration files.

This tool utilizes a parser to traverse the JSON structure, checking for syntax errors like missing commas, incorrect brackets, or invalid data types. If the input parses, it is printed back with 2-space indentation along with the key count, nesting depth and size in bytes; if it does not, the tool shows Invalid with the parser's error message and makes no attempt to repair it.

Always validate your JSON before using it in production environments to catch subtle syntax errors. Be aware that even a single misplaced comma or bracket can render an entire JSON payload invalid, leading to application failures.

Example: Validating and Formatting an API Response

  1. 1 Input: {"user":"Jane Doe", "age":30, "email":"[email protected]" "city":"New York"}
  2. 2 The comma between the "email" and "city" members is missing, so parsing fails: the status reads Invalid and no formatted output appears. The error message comes from your browser's JSON parser; Chrome, for example, reports that it expected ',' or '}' after the property value at position 61.
  3. 3 After you add the comma, the status changes to Valid JSON and the formatted output is: { "user": "Jane Doe", "age": 30, "email": "[email protected]", "city": "New York" }
  4. 4 JSON Stats for the corrected input: 4 keys, maximum depth 1, size 80 bytes. The tool points to the error but leaves the fix to you.

Source: RFC 8259 — The JavaScript Object Notation (JSON) Data Interchange Format (IETF, 2017) · Last updated: September 2026

Frequently Asked Questions

How do you format JSON for readability?
Use indentation (2 or 4 spaces) for nested objects and arrays. Paste your JSON into this formatter to auto-indent it and validate the syntax; if it is invalid, the parser's error message tells you where it stopped. Most code editors also have built-in JSON formatting.
What are common JSON syntax errors?
The most common errors are trailing commas after the last item, single quotes instead of double quotes, unquoted keys, and missing commas between items. JSON requires double quotes for all strings and keys.
What is the difference between JSON and a JavaScript object?
JSON requires double-quoted keys and string values, does not allow trailing commas, and cannot contain functions or undefined. JavaScript objects are more flexible. JSON is a strict subset of JavaScript object notation.

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