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JSON Formatter & Validator

Instantly beautify, minify, and validate JSON. Paste your JSON, choose your indent style, and get clean output in one click. All processing happens in your browser — nothing is sent to a server.

Input JSON

Output

Ready — paste JSON and click Format

Try a sample: Simple Object Array of Objects Nested / Complex Minified JSON API Response

📊 JSON Stats

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Keys

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⌨️ Shortcuts

Ctrl+EnterFormat JSON

Ctrl+MMinify JSON

Ctrl+Shift+CCopy output

Ctrl+LClear all

TabInsert indent in editor

💡 JSON Tips

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Keys must be strings wrapped in double quotes — single quotes are not valid JSON.

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No trailing commas — a comma after the last item in an array or object causes a parse error.

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Numbers don't need quotes. 42 and "42" are different types.

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100% private — all processing runs in your browser. Nothing is ever uploaded.

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What is a JSON Formatter?

A JSON formatter (also called a JSON beautifier or JSON pretty printer) takes raw, compact, or minified JSON text and re-outputs it with consistent indentation and line breaks, making it easy for humans to read and debug. It can also validate that the JSON is syntactically correct, catching issues like missing quotes, trailing commas, or mismatched brackets before they cause bugs in your application.

This tool runs entirely in your browser using the built-in JSON.parse() and JSON.stringify() APIs — your data never leaves your machine.

Format vs Minify — When to Use Each

Format / Beautify — use when debugging API responses, reading config files, or reviewing data structures. Indentation makes nesting immediately clear.
Minify — use before sending JSON in HTTP responses, storing in a database, or embedding in source code. Removes all whitespace to reduce file size.
Validate only — use in CI/CD pipelines or when you just need to confirm a file is valid before processing it.

Frequently Asked Questions

The most common JSON errors are: (1) using single quotes instead of double quotes for strings or keys, (2) a trailing comma after the last item in an array or object, (3) using undefined as a value (not allowed — use null), (4) unescaped special characters like backslashes or newlines inside string values, and (5) comments — JSON does not support // or /* */ comments.

Yes — completely. All formatting and validation runs in your browser using JavaScript's native JSON APIs. Nothing is sent to any server. You can verify this by disconnecting from the internet and the tool will still work perfectly.

JSON is a strict text format derived from JavaScript object syntax, but with important differences: all keys must be double-quoted strings, values must be one of string, number, boolean, null, array, or object — functions, undefined, and Date objects are not valid JSON values. A JavaScript object literal can use unquoted keys, single quotes, trailing commas, and functions, which is why object literals from JS source code often fail JSON validation.

2 spaces is the most common choice for JSON config files (used by npm, ESLint, Prettier defaults). 4 spaces follows the Python and Java convention. Tabs save bytes and respect editor tab-width preferences. For machine-consumed JSON like API payloads, minify instead — whitespace adds unnecessary size.

Yes, but browser performance degrades for files above ~5MB when using a textarea. For files larger than that, consider using a dedicated editor like VS Code (Shift+Alt+F to format) or a command-line tool like python3 -m json.tool file.json or jq . file.json.