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JSON Formatter & Viewer — Free Online

Format, prettify, minify, and validate JSON instantly with this free online JSON formatter. Adjust indentation, sort keys, and view stats in real time.

Input: 69 chars | Minified: 55 chars

What is a JSON Formatter?

A JSON formatter is a tool that takes raw or compact JSON (JavaScript Object Notation) and displays it in a human-readable, properly indented format. JSON is the most widely used data-interchange format on the web, used by REST APIs, configuration files, NoSQL databases, and message queues. Raw JSON returned by APIs is often minified — all whitespace removed — to save bandwidth, making it nearly impossible to read. A JSON formatter parses the string, validates its syntax, and re-serializes it with consistent indentation (typically 2 or 4 spaces). This tool also supports minification (removing all unnecessary whitespace) and key sorting, which is useful for comparing two JSON objects or producing deterministic output.

How to Use This Free Online JSON Formatter

  1. Paste or type your JSON into the input text area. The tool validates it in real time and shows any syntax errors immediately.
  2. Choose the output view: 'Formatted' for pretty-printed JSON with your chosen indentation, or 'Minified' for the most compact representation.
  3. Select your preferred indent size: 2 spaces, 4 spaces, or tab characters.
  4. Toggle 'Sort keys' to alphabetically order all object keys — useful for diffing or canonical JSON output.
  5. Click the Copy button to copy the formatted or minified result to your clipboard.

Common Use Cases for JSON Formatting

  • Debugging API responses — Paste minified JSON from API responses to quickly inspect nested structures, find missing fields, or spot incorrect data types.
  • Cleaning up configuration files — Reformat messy JSON config files (package.json, tsconfig.json, etc.) with consistent indentation before committing to version control.
  • Comparing JSON payloads — Sort keys and format two JSON objects identically so you can diff them line by line to find differences.
  • Minifying JSON for storage — Remove all whitespace from JSON before storing it in databases or transmitting over the network to reduce payload size.
  • Validating JSON syntax — Quickly check whether a JSON string is valid before using it in code, configurations, or API requests.

FAQ

What makes JSON invalid?
Common causes of invalid JSON include: trailing commas after the last item in an array or object, single quotes instead of double quotes around strings, unquoted property names, comments (JSON does not support comments), and missing or extra brackets/braces. This tool will show the exact error and position to help you fix it.
What is the difference between JSON.stringify with 2 spaces and 4 spaces?
The number of spaces controls the indentation depth of each nesting level. 2 spaces produce more compact output that fits more data on screen, while 4 spaces provide greater visual separation between levels. The choice is a style preference — many JavaScript projects use 2 spaces, while Java and Python ecosystems often prefer 4.
Does sorting keys change the meaning of the JSON?
No. The JSON specification (RFC 8259) states that objects are unordered collections of key-value pairs, so reordering keys does not change the semantic meaning. However, some applications may rely on insertion order, so use sort with caution in those contexts.
Is this tool free and private?
Yes. All formatting, minification, and validation happen entirely in your browser using JavaScript's built-in JSON.parse and JSON.stringify. No data is sent to any server, and no sign-up is required.

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