JSON (JavaScript Object Notation) is a lightweight, human-readable data interchange format. It is based on JavaScript object syntax but is language-independent and supported by virtually every programming language. JSON uses key-value pairs, arrays, strings, numbers, booleans, and null values.

What is the difference between JSON formatting and minifying?

Formatting (beautifying) adds indentation and line breaks to make JSON human-readable. Minifying removes all whitespace and newlines to reduce file size for transmission or storage. Both produce valid JSON — only the presentation differs.

Valid JSON must have keys quoted in double quotes (not single quotes), no trailing commas after the last element, no comments (// or /* */), and correct nesting of objects and arrays. Common mistakes include using single quotes, trailing commas, and unquoted keys.

What is the difference between JSON and JavaScript objects?

JavaScript objects allow unquoted keys, single quotes, functions, undefined, and trailing commas. JSON requires double-quoted keys, only supports strings, numbers, booleans, null, objects, and arrays — no functions, no undefined, and no comments.

How do I fix a JSON parse error?

Common fixes: 1) Replace single quotes with double quotes around keys and string values. 2) Remove trailing commas after the last item in an object or array. 3) Remove comments (JSON does not support // or /* */). 4) Make sure all strings are closed with matching quotes. 5) Check for missing commas between key-value pairs.

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Formatter

JSON Formatter & Validator

Paste any JSON to instantly pretty print, minify, or validate it with this free online JSON formatter. Syntax errors are detected and displayed with exact line and column numbers so you can fix issues fast. Features include customizable indentation (2 spaces, 4 spaces, or tabs), alphabetical key sorting, full syntax highlighting with color-coded tokens, and real-time JSON statistics showing size, key count, array count, and nesting depth. All formatting happens entirely in your browser — no data is sent to any server. Works offline, no signup required.

json-formatter.tool

Indent

Sort keys A–Z

JSON Input

0 characters

Output

Output will appear here...

How to use the JSON formatter

Whether you're debugging a malformed API response or reviewing a config file, the workflow is the same: paste, format, fix any errors flagged, and copy. The formatter never sends data to a server, so even production payloads with sensitive customer info can be pasted safely.

1. Paste your JSON in the input area. It can be minified, escaped, or already-pretty — the formatter accepts all three.
2. Click "Format" (or it auto-formats on paste). Output is indented 2 spaces by default; switch to 4 spaces or tabs if your team's style guide differs.
3. Read the error pointer if validation fails. The line and column of the first parse error appear above the output, with a syntax-highlighted excerpt.
4. Use "Minify" when you need the opposite — strip whitespace before embedding JSON in a URL, header, or string literal.
5. Copy the output with one click. The formatter preserves Unicode escapes (\uXXXX) and number precision exactly as input.

Common JSON mistakes to avoid

Trailing commas. JSON forbids them — {"a": 1,} is invalid. JS5 and YAML allow them, which trips people up. Strip before saving.
Single quotes around keys or strings. JSON requires double quotes. {'key': 'value'} is JS object literal syntax, not JSON.
Unquoted keys. {key: 1} works in JS but breaks every JSON parser. Always quote keys: {"key": 1}.
Comments inside JSON. Standard JSON has no // comments or /* */. If you need them, switch to JSON5 or JSONC and document the dependency.
Numbers larger than Number.MAX_SAFE_INTEGER. JS loses precision past 2⁵³. Server IDs and Discord snowflakes need to be quoted as strings to survive the round-trip.
Mixing UTF-8 and escaped Unicode. "é" and "\u00e9" are equivalent but produce different bytes. Pick one consistently for diff-friendly storage.

Frequently Asked Questions

What is JSON?

JSON (JavaScript Object Notation) is a lightweight, human-readable text format for storing and transmitting data. It consists of key-value pairs in objects {"key": "value"} and ordered arrays [1, 2, 3]. JSON supports six data types: string, number, boolean, null, object, and array. It's the dominant data format for REST APIs, configuration files, and database storage.

What are the most common JSON errors?

The top JSON errors are:
1. Single quotes — JSON requires double quotes around keys and strings. 'name' → "name"
2. Trailing commas — {"a": 1,} is invalid. Remove the comma after the last item.
3. Unquoted keys — {name: "John"} is JavaScript, not JSON. Keys must be quoted.
4. Comments — JSON does not support // or /* */.
5. Undefined/NaN/Infinity — these JavaScript values are not valid JSON.

What is the difference between JSON pretty print and minify?

Pretty print adds indentation and line breaks, making JSON readable for humans. Use it for debugging, config files, and documentation. Minify removes all whitespace and newlines, reducing file size for network transmission. Minified JSON can be 20–30% smaller. Both produce equivalent data — only formatting differs.

Does JSON support comments?

No. Standard JSON (RFC 8259) does not support comments. This is intentional — JSON was designed as a data format, not a configuration format. If you need comments in config files, consider JSONC (JSON with Comments, used by VS Code), YAML, or TOML instead.

How do I parse JSON in JavaScript, Python, and Go?

JavaScript: const obj = JSON.parse(jsonString); — and serialize with JSON.stringify(obj, null, 2)
Python: import json; obj = json.loads(json_string) — serialize: json.dumps(obj, indent=2)
Go: import "encoding/json"; json.Unmarshal([]byte(jsonString), &obj)
PHP: $obj = json_decode($jsonString, true);

Is my JSON data safe to paste here?

Yes. All processing is done entirely in your browser using JavaScript's built-in JSON.parse() and JSON.stringify() APIs. No data is ever sent to a server. The tool works fully offline. We strongly recommend not pasting production secrets or API keys into any online tool — as a general security practice.

JSON Formatter & Validator

How to use the JSON formatter

Common JSON mistakes to avoid

Frequently Asked Questions

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