JSON Formatter

Format, validate, prettify, and minify your JSON data quickly.

Input JSON

Output Result

How to Use

Paste your JSON data

Input raw, minified, or potentially broken JSON from an API, config file, or any source.

Format or validate

Click Beautify to pretty-print with indentation, or check for syntax errors with detailed error messages.

Copy or minify the result

Copy the formatted JSON for debugging, or minify it to remove whitespace for production use.

Use for API debugging

Paste raw API responses to quickly inspect nested object structures and data types.

What is JSON?

JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write, and it is easy for machines to parse and generate. However, raw JSON files or API outputs are often "minified" (compressed into a single line) to save bandwidth, making them nearly impossible to read for developers debugging an issue.

Validate Your Code

This tool not only formats (beautifies) your JSON by adding proper indentation and spacing, but it also validates it against strict JSON specifications. If you have a missing comma or an unclosed bracket, our formatter will instantly catch the syntax error so you can fix it before deploying.

Real-World Examples & Use Cases

API Response Debugging and Inspection

When calling REST APIs during development, the response body is often minified JSON compressed onto a single line for efficiency. Developers need to format this to inspect the data structure, verify field names, check data types, and identify missing or unexpected values. A JSON formatter transforms unreadable minified API responses into properly indented trees where nested objects and arrays are immediately visible, reducing debugging time significantly.

Configuration File Editing and Validation

Modern applications use JSON for configuration: package.json in Node.js, launch.json in VS Code, appsettings.json in .NET, and countless service configuration files. A misplaced comma or missing bracket causes the entire application to fail to start, often with a cryptic parse error. A JSON formatter validates the config file and pinpoints the exact location of syntax errors, saving developers from hunting through hundreds of lines for a missing quotation mark.

Data Pipeline and ETL Development

Data engineers building ETL (Extract, Transform, Load) pipelines frequently work with JSON data from databases, log files, and event streams. Formatting and validating the JSON schema before writing transformation logic ensures the input data structure matches expectations. A JSON formatter helps verify that nested objects, arrays of objects, and nullable fields are exactly as the pipeline expects before writing parsing code that depends on specific field paths.

Learning and Teaching JSON Structure

Students and developers new to JSON benefit from seeing properly indented, formatted examples to understand how nesting, arrays, and key-value pairs work together. A JSON formatter makes the hierarchy visually apparent: each nesting level is indented one level deeper, opening braces are matched with closing braces, and array items are listed one per line. This visual learning is much more effective than reading a flat minified string.

How It Works

JSON Specification (RFC 8259): JSON supports exactly 6 value types: 1. string — "hello world" (double-quoted, supports escape sequences) 2. number — 42, 3.14, -1, 1.5e10 (no hex, no NaN, no Infinity) 3. boolean — true, false (lowercase only) 4. null — null (lowercase only) 5. array — [value1, value2, ...] 6. object — {"key": value, ...} (keys must be strings) Common syntax errors caught: - Trailing commas: {"a": 1,} ← invalid JSON (valid JS) - Single quotes: {'a': 1} ← invalid (must use double quotes) - Unquoted keys: {a: 1} ← invalid (JS shorthand, not JSON) - Comments: // or /* */ ← invalid (JSON has no comments) - undefined value ← not a JSON type Formatting algorithm: 1. Parse JSON string to AST using JSON.parse() 2. If parse error: return error with position 3. Re-serialize with JSON.stringify(obj, null, 2) The third parameter sets indentation (2 = 2 spaces) Minification: json.replace(/\s+/g, '') is too naive (breaks strings with spaces) Correct approach: JSON.stringify(JSON.parse(json)) — re-serialize with no indentation

Frequently Asked Questions

What is the difference between formatting and validating JSON?▼

Formatting (also called beautifying or pretty-printing) adds indentation and line breaks to make JSON human-readable without changing its data. Validating checks whether the JSON syntax is correct — detecting issues like missing commas, extra commas, unmatched brackets, or invalid value types. A formatter and validator combined first validates (and shows errors for broken input), then formats valid input. Minifying is the reverse of formatting: it removes all unnecessary whitespace to reduce file size.

Why is my JavaScript object not valid JSON?▼

JavaScript object literals look similar to JSON but have key differences. JavaScript allows: trailing commas after the last item ({a: 1,}), unquoted keys ({a: 1}), single-quoted strings ({'a': 1}), undefined values, comments, and special values like NaN and Infinity. JSON requires: all keys in double quotes, no trailing commas, only double-quoted strings, no undefined, no comments, numbers must be finite. JSON.stringify() converts a JS object to valid JSON, automatically removing undefined values and non-serializable types.

How do I format deeply nested JSON without a tool?▼

In the terminal: python3 -m json.tool file.json or cat file.json | python3 -m json.tool. In Node.js: JSON.stringify(JSON.parse(input), null, 2). In the browser console: JSON.stringify(data, null, 2). Most code editors can format JSON with a keyboard shortcut (VS Code: Shift+Alt+F). However, an online formatter is faster for quick inspection of API responses — no need to open a terminal or IDE.

What is JSON5 and JSONC?▼

JSON5 and JSONC are relaxed supersets of JSON that add JavaScript-style conveniences. JSON5 allows: unquoted keys, single quotes, trailing commas, comments (// and /* */), and more number formats. JSONC (JSON with Comments) adds only comment support. VS Code's settings.json uses JSONC. These formats are NOT valid standard JSON and will fail with JSON.parse(). They require dedicated parsers (the json5 npm package, etc.). A standard JSON formatter will reject JSONC/JSON5 as invalid — look for a dedicated JSON5 formatter for those.

Is it safe to paste sensitive data into an online JSON formatter?▼

Exercise caution when pasting JSON containing API keys, passwords, personal data (PII), or proprietary business data into any online tool. A privacy-focused formatter that processes data entirely in your browser (no server upload) is safer for general development data. For highly sensitive production data (auth tokens, medical records, financial data), use a local tool: your code editor's built-in formatter, the command-line Python JSON tool, or a VS Code extension. Check the tool's privacy policy and look for 'all processing done in browser' indicators.

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