What is a JSON formatter?

A JSON formatter (also called JSON beautifier or pretty printer) takes compact or messy JSON data and reformats it with proper indentation and line breaks, making it human-readable. It typically also validates the JSON to ensure it's syntactically correct. Our online JSON formatter adds syntax highlighting and error detection.

How do I format JSON online?

Simply paste your JSON into our formatter and it instantly formats it with proper indentation. You can choose 2-space, 4-space, or tab indentation. Click 'Minify' to compress it, or 'Copy' to copy the formatted result. The formatter also highlights any syntax errors with line numbers.

How do I validate JSON?

Our JSON formatter automatically validates your JSON as you type. If there's an error, it shows the exact error message and position (line and column). Common JSON errors include: trailing commas after the last item, single quotes instead of double quotes, unquoted keys, and missing closing brackets.

What is the difference between JSON format and minify?

Formatting (pretty printing) adds indentation and line breaks to make JSON readable. Minifying removes all unnecessary whitespace to make the JSON as compact as possible. Formatting is for development and debugging; minifying is for production to reduce file size and network payload.

Why is my JSON invalid?

Common reasons JSON is invalid: 1) Trailing commas: {"a":1} — remove the last comma. 2) Single quotes: {'key':'value'} — use double quotes. 3) Unquoted keys: {key: "value"} — quote all keys. 4) Missing brackets or braces. 5) Using undefined or NaN — use null instead. Our JSON validator shows the exact error location.

Can I format large JSON files?

Yes, our JSON formatter handles large JSON files efficiently in the browser. For very large files (10MB+), formatting may take a moment. The tool processes everything client-side — your data never leaves your browser, making it safe for sensitive JSON data like API keys or user data.

What indentation should I use for JSON?

2 spaces is the most common JSON indentation (used by npm, many APIs, and most JavaScript projects). 4 spaces is used in some enterprise codebases for extra readability. Tabs are less common for JSON but supported. For production/APIs, use minified JSON (no indentation) to save bandwidth.

JSON Formatter

Our JSON formatter is a fast, free online tool for developers to format, validate, and minify JSON data. Paste your JSON and instantly see it pretty-printed with syntax highlighting. The validator pinpoints exact error locations with line numbers, making it easy to fix malformed JSON. Supports 2-space, 4-space, and tab indentation, plus one-click minification for production use.

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calendar_today Updated: April 2026

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Indent:

info Paste JSON to format

0 lines 0 B 0 keys depth 0

Input Values

JSON Input

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JSON Analysis:

Status: Valid JSON
Structure: Object with nested properties
Size: Formatted for readability

Tip: Use 2-space indentation for most projects, minify for production APIs.

lightbulb Tips

•JSON keys must use double quotes
•Trailing commas are not valid JSON
•Use 2-space indent for most projects
•Minify JSON for API payloads

How to Use This Calculator

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Paste JSON

Paste your raw or messy JSON into the input editor. Supports any valid (or invalid) JSON text.

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Format or Minify

Click Format to pretty-print with your chosen indentation, or Minify to compress. Errors are highlighted automatically.

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Copy Result

Click the Copy button to copy formatted JSON to your clipboard. Use in your code, API requests, or config files.

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Fix Errors

If JSON is invalid, the error message shows the exact line and position. Fix the issue and re-format.

The Formula

JSON formatting works by parsing the raw JSON string into a JavaScript object (which validates it), then re-serializing it with proper indentation. If parsing fails, the error message includes the position of the syntax error. Minification removes all whitespace by using no indentation.

JSON.parse(input) → JSON.stringify(parsed, null, indent)

lightbulb Variables Explained

input Raw JSON string to be formatted
JSON.parse() Validates and parses JSON — throws error if invalid
JSON.stringify() Converts parsed object back to formatted string
indent Number of spaces (2 or 4) or tab character for indentation

tips_and_updates Pro Tips

Use 2-space indentation for compact files, 4-space for readability

Minify JSON before sending in API requests to reduce payload size

Common errors: trailing commas, single quotes, and unquoted keys are not valid JSON

Use Ctrl+A to select all, then paste — the formatter handles any whitespace

JSON keys must always be double-quoted strings — {key: value} is not valid JSON

Arrays and objects can be empty: [] and {} are valid JSON

null, true, false are valid JSON values — but undefined is not

Format, Validate & Minify JSON Online

Our free JSON formatter instantly pretty-prints, validates, and minifies your JSON data. Features syntax highlighting, error detection with line numbers, customizable indentation, and one-click copy. All processing happens in your browser — your data stays private.

JSON Formatter & Pretty Printer

Paste messy or compact JSON and get perfectly formatted output with proper indentation. Choose 2 spaces, 4 spaces, or tabs. Our JSON formatter handles nested objects, arrays, and large files with instant formatting and syntax highlighting.

JSON Validator with Error Detection

Our JSON validator checks your JSON syntax and pinpoints exact error locations with line numbers and descriptions. Catch trailing commas, missing quotes, unmatched brackets, and other common JSON errors before they break your API calls or config files.

JSON Minifier for Production

Minify your JSON to remove all whitespace and reduce file size. Essential for API responses, configuration files, and data transfer. Our minifier preserves data integrity while creating the most compact representation possible.

Frequently Asked Questions

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