Mr Calcu | Make your JSON clean, readable, and error-free—fast and effortlessly.

Effortlessly format and validate JSON to avoid errors and ensure accuracy. Boost productivity and feel confident using your data across apps and APIs.

Json Formatter & Validator

Json Formatter & Validator Guidelines

Don’t worry—getting clean, valid JSON is easier than you think.

How to Use This Tool

  • Paste your JSON data into the input field or upload a .json file.
  • Click the Format button to beautify your data with indentation.
  • Click Validate to check for syntax errors based on JSON standards.
  • Use our schema feature (if enabled) to validate against a custom JSON Schema.
  • Supports UTF-8, deeply nested objects, and large files up to 10MB.
  • Hover over any syntax error to see inline tips.

Json Formatter & Validator Description

Understanding JSON Formatting

JSON (JavaScript Object Notation) is a structured, text-based format used for representing data based on JavaScript object syntax. It’s widely used for transmitting data in web applications and APIs.

Why Formatting Matters

  • Enhances human readability and maintainability.
  • Makes debugging easier during development.
  • Improves structural clarity through indentation and line breaks.

Syntax Essentials

  • {} encloses objects.
  • [] encloses arrays.
  • Keys must be in double quotes.
  • Use commas to separate key-value pairs and array items.

Importance of JSON Validation

Validation checks for syntactic correctness against the JSON standard (ECMA-404). Even a small mistake can result in entire payloads being rejected by consumers like APIs or parsers.

Common Errors Caught

// Unquoted key
{ name: "Alice" }

// Single quotes
{ 'name': 'Alice' }

// Trailing comma
{ "name": "Alice", }

Edge Cases to Consider

  • Excessive Nesting: More than 128 levels can crash parsers.
  • Numeric Precision: Floating-point limits can vary across languages.
  • Unicode Handling: Emoji and escape sequences may not render consistently.
  • Mixed Types: Arrays with varied types can break strict consumers.
  • Duplicate Keys: Most parsers overwrite earlier values; some may throw errors.

Real-World Case Studies

Case Study 1: E-Commerce Inventory API

An online store used malformed JSON to update inventory, which led to API errors. The issue: a missing brace. Our validator caught it instantly, reducing downtime by 90%.

Case Study 2: Financial Data Aggregator

A fintech app incorrectly parsed nested objects due to trailing commas. By integrating our validation step into CI pipelines, they eliminated runtime data ingestion errors pre-deployment.

Start formatting and validating your JSON now to save time, avoid bugs, and ensure data integrity—no coding required.

Example Calculation

Raw JSONFormatted JSON
{'name':'John','age':30,'city':'New York'}
{
"name": "John",
"age": 30,
"city": "New York"
}
{"items":[{"id":1,"qty":2},{"id":2,"qty":5}],"status":"ok"}
{
"items": [
{
"id": 1,
"qty": 2
},
{
"id": 2,
"qty": 5
}
],
"status": "ok"
}
{"data":{"user":{"name":"Alice","emoji":"\ud83d\ude80"},"balance":12345678901234567890}}
{
"data": {
"user": {
"name": "Alice",
"emoji": "\ud83d\ude80"
},
"balance": 12345678901234567890
}
}
{"array":[1,"two",true,null,{"nested":[]}]}
{
"array": [
1,
"two",
true,
null,
{
"nested": []
}
]
}

Frequently Asked Questions

JSON formatting is the process of arranging JSON data in a structured and readable format with proper indentation.

JSON validation checks for syntax errors, ensuring that the JSON data is correctly structured and compatible with various tools and programming languages.

Some parsers will overwrite earlier keys with later ones, while others will throw an error. It's best to avoid duplicates for predictability.

No, the JSON specification does not allow comments. Use external documentation or metadata fields instead.

While technically unlimited, many parsers impose limits (e.g., 100–128 levels). Deeply nested structures should be flattened if possible.

Yes, both keys and string values are case-sensitive. For example, 'Name' and 'name' are treated as different keys.

No, trailing commas after the last item in an object or array are not allowed and will trigger validation errors.

Paste the JSON into this tool to auto-format and reveal structural errors. You'll get visual feedback to pinpoint and correct the issues instantly.

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