JSON Formatter & Validator
Beautify, minify, and validate your JSON data instantly. Find syntax errors with precise line numbers.
JSON Validation Error
How to Use the JSON Formatter
- Paste your JSON — Paste your raw, unformatted JSON into the left input panel. You can paste data from APIs, config files, database exports, or any JSON source.
- Click Format — Click the Format / Prettify button. The tool validates your JSON, shows any errors with line numbers, and displays the formatted result with syntax highlighting.
- Copy the result — Click Copy Output to copy the formatted JSON to your clipboard. Use it in your code editor, documentation, or API requests.
How JSON Formatting Works
JSON (JavaScript Object Notation) is a lightweight data interchange format used by virtually every modern API and configuration system. When JSON is transmitted over networks or generated by machines, it is often minified — stripped of all whitespace and line breaks — to reduce file size. While this is efficient for machines, it makes the data nearly impossible for humans to read or debug.
A JSON formatter parses the raw string, validates it against the JSON specification (RFC 8259), and reconstructs it with consistent indentation (typically 2 spaces), line breaks after each element, and proper nesting. This process is called pretty-printing or beautifying. The formatter also detects syntax errors such as missing commas, trailing commas, unmatched brackets, and incorrect string escaping, reporting the exact line number where the error occurs.
Common Use Cases
- API debugging — Quickly format JSON responses from REST APIs to inspect data structures, find missing fields, or verify nested objects.
- Configuration files — Prettify package.json, tsconfig.json, or other config files to make them readable and easier to edit.
- Data cleaning — Validate JSON data before importing it into databases, data pipelines, or analytics tools.
- Code review — Format JSON snippets in documentation, pull requests, or messages for clear communication.
Did You Know?
The JSON.stringify() function built into JavaScript can format JSON with a second parameter for indentation. Passing null, 2 as arguments produces the same output as this formatter. However, this tool adds syntax highlighting and error reporting with exact line numbers, which the native function does not provide.
JSON Data Types
| Type | Description | Example |
|---|---|---|
| String | Text enclosed in double quotes | "Hello, World!" |
| Number | Integer or decimal (no quotes) | 42 or 3.14 |
| Boolean | True or false values | true or false |
| Array | Ordered list of values in brackets | ["apple", "banana", "cherry"] |
| Object | Key-value pairs in curly braces | {"name": "John", "age": 30} |
| Null | Represents an empty or missing value | null |
Common JSON Errors
| Error Message | Cause | Fix |
|---|---|---|
| Unexpected token ',' | Trailing comma after the last item | Remove the comma before } or ] |
| Unexpected token in JSON | Single quotes used instead of double | Replace all ' with " |
| Expected ':' after property name | Missing colon between key and value | Add : after every key |
| Unexpected end of JSON input | Missing closing bracket or brace | Check that every { has a } and every [ has a ] |
| Bad control character in string | Newlines or tabs inside a string | Escape with \n or \t |
| Unexpected token '}' | Empty object with trailing comma {,} | Remove the comma: {} |
| Property name must be a string | Unquoted key names | Wrap all keys in double quotes |
JSON vs Other Data Formats
| Feature | JSON | XML | YAML | TOML |
|---|---|---|---|---|
| File Extension | .json | .xml | .yaml / .yml | .toml |
| Readability | Good | Verbose | Excellent | Excellent |
| Data Types | String, Number, Bool, Array, Object, Null | All text (needs schema) | Same as JSON + dates, binary | String, Int, Float, Bool, DateTime, Array |
| Comments | Not supported | <!-- comment --> | # comment | # comment |
| Human Writable | Moderate | Difficult | Easy | Easy |
| APIs / REST | Standard (most APIs) | Legacy / SOAP | Rare | Not used |
| Config Files | package.json, tsconfig | pom.xml, web.xml | Docker Compose, K8s | Cargo.toml, pyproject |
| Schema Validation | JSON Schema | XSD, DTD | JSON Schema (partial) | Built-in types |
| File Size | Compact | Large (tags) | Compact | Compact |
Frequently Asked Questions
What is a JSON formatter?
A JSON formatter is a tool that takes raw, unformatted JSON data and restructures it with proper indentation, line breaks, and spacing. This makes the JSON human-readable and easier to debug. It also validates the syntax and highlights any errors.
Is this JSON formatter free to use?
Yes, this JSON formatter is completely free with no signup required. You can format, validate, and minify unlimited JSON data directly in your browser.
Is my JSON data safe when using this tool?
Yes, your data is completely safe. All JSON processing happens locally in your browser using JavaScript. No data is sent to any server, ensuring complete privacy.
What is the difference between formatting and minifying JSON?
Formatting (or prettifying) adds indentation and line breaks to make JSON readable. Minifying removes all unnecessary whitespace to create the smallest possible file size, which is useful for production APIs and data transfer.
Can this tool fix broken JSON?
This tool validates JSON and shows you exactly where errors occur with line numbers. While it cannot automatically fix broken JSON, it helps you identify the exact location of syntax errors like missing commas, unmatched brackets, or incorrect quoting.
More Free Tools
Word Counter
Count words, characters & sentences
Case Converter
Convert text case instantly
Online Notepad
Quick notes with auto-save
Color Picker
Pick, convert & generate color palettes
Unit Converter
Convert between 8+ unit categories
Percentage Calculator
Calculate percentages easily
Loan Calculator
EMI & interest calculations
Age Calculator
Calculate age from date of birth
QR Code Generator
Create & download QR codes free
Password Generator
Generate secure random passwords
Timer & Stopwatch
Online timer with alarm & lap tracking