✦ToolMagic

JSON Formatter

Prettify, validate, and minify JSON data with tree view, adjustable indentation, and instant error detection.

What is a JSON Formatter?

A JSON formatter online is a developer tool that takes raw, unformatted JSON data and presents it in a clean, readable format with proper indentation and structure. JSON (JavaScript Object Notation) is the most widely used data format for APIs, configuration files, and data exchange, but raw JSON from APIs or minified files is often a single long line that's impossible to read. This JSON pretty print tool instantly formats your JSON with customizable indentation (2 spaces, 4 spaces, or tabs), validates it with detailed error messages, offers a minify option to compress JSON for production use, and provides an interactive tree view for navigating complex data structures. It also shows useful stats like total keys, nesting depth, and data size. Everything runs client-side in your browser — your JSON data is never sent to any server.

How to Use the JSON Formatter

  1. Paste or upload JSON: Paste your JSON data into the input field, or click "Upload File" to load a .json file from your device.
  2. Check validation: If your JSON has errors, a detailed error message appears below the input showing what went wrong.
  3. Choose indentation: Select 2 spaces, 4 spaces, or tabs from the dropdown to control the formatting style.
  4. Switch views: Toggle between "Formatted" (pretty-printed code) and "Tree View" (interactive collapsible hierarchy).
  5. Review stats: Check the total keys, max depth, and data size displayed between the controls and output.
  6. Copy results: Click "Copy Formatted" for pretty-printed JSON or "Copy Minified" for compressed output.

Features

  • JSON pretty print: Format raw JSON with proper indentation for easy reading and debugging.
  • JSON validation: Instant validation with clear error messages when your JSON is malformed.
  • Minification: Compress formatted JSON into a single line for production use, reducing file size.
  • Interactive tree view: Navigate complex JSON structures with collapsible nodes, color-coded by data type.
  • Adjustable indentation: Choose between 2 spaces, 4 spaces, or tab indentation to match your coding style.
  • File upload: Load .json files directly from your device instead of copy-pasting.
  • Data statistics: View total keys, maximum nesting depth, and data size at a glance.
  • One-click copy: Copy either formatted or minified output to clipboard instantly.
  • 100% client-side: Your JSON data never leaves your browser. Complete privacy guaranteed.

Use Cases

  • API development: Format API responses from tools like Postman, curl, or browser DevTools to inspect data structures and debug issues.
  • Configuration files: Prettify package.json, tsconfig.json, and other config files for easier editing and code review.
  • Data analysis: Navigate large JSON datasets with tree view to understand structure and find specific values.
  • Bug reports: Format JSON payloads and error responses for inclusion in bug reports and documentation.
  • Learning & teaching: Visualize JSON structure with tree view to understand nested data, arrays, and objects.

Tips & Tricks

  • Use the tree view to quickly find deeply nested values without scrolling through hundreds of lines of formatted JSON.
  • The validation error message often includes the position (character number) where the error occurred — look there first.
  • Common JSON errors: trailing commas after the last item, single quotes instead of double quotes, and unquoted keys.
  • Use "Copy Minified" when you need to embed JSON in URLs, environment variables, or database fields where size matters.
  • Combine with the Unix Timestamp Converter to decode timestamp fields you find in JSON data.

JSON Formatter vs Alternatives

Tools like jsonformatter.org and jsonlint.com have been around for years but often feel outdated, run slowly, and are filled with ads. ToolMagic's JSON formatter offers a modern, clean interface without distracting ads, includes both formatted and tree views in one tool, runs entirely client-side for maximum speed and privacy, and provides data statistics (keys, depth, size) that most alternatives lack. Unlike browser extensions, it requires no installation and works on any device.

Frequently Asked Questions

How do I format JSON online?

Simply paste your raw JSON into the input field. It's instantly formatted with proper indentation. Choose between 2 spaces, 4 spaces, or tab indentation using the dropdown. Click "Copy Formatted" to grab the result.

How do I validate JSON?

Paste your JSON into the input. If it's valid, you'll see the formatted output. If it's invalid, a red error message appears with details about what's wrong and where the error is located.

How do I minify JSON?

Paste your JSON, wait for it to validate, then click "Copy Minified." This copies a compressed version with all whitespace removed, perfect for production use.

What is JSON tree view?

Tree view displays your JSON as an interactive, collapsible hierarchy. Click on objects and arrays to expand or collapse them. Values are color-coded by type (strings in green, numbers in blue, etc.).

Can I upload a JSON file?

Yes! Click the "Upload File" link above the input area and select a .json or .txt file from your device. The content is loaded into the editor for formatting.

Is my JSON data secure?

Absolutely. All processing happens locally in your browser. Your JSON is never sent to any server. This makes it safe for formatting sensitive data like API keys and configuration files.

What are common JSON errors?

The most common errors are: trailing commas (not allowed in JSON), using single quotes instead of double quotes, unquoted property names, and missing closing brackets or braces.

What do the stats (keys, depth, size) mean?

"Total Keys" counts all property names across all objects. "Max Depth" shows how deeply nested the data is. "Size" shows the byte size of your input data.

Related Tools

Explore more free developer tools on ToolMagic: use the Unix Timestamp Converter to decode epoch timestamps, the Binary Translator to convert between number systems, or the Case Converter to transform text between camelCase, snake_case, and more.