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JSON Formatter & Validator

Format, validate and minify JSON data online. Free JSON beautifier with syntax highlighting.

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What is a JSON Formatter?

A JSON formatter (also called JSON beautifier or pretty-printer) takes compact or malformed JSON data and reformats it with proper indentation, line breaks, and structure. This makes deeply nested objects and arrays readable at a glance. The tool also validates your JSON against the specification, catching syntax errors like trailing commas, unquoted keys, or mismatched brackets before they cause runtime failures in your application.

How to Use This Tool

  1. Paste your JSON into the left input panel — it can be minified, poorly formatted, or copied from a network response.
  2. Click "Format" to beautify with 2-space indentation, "Minify" to compress, or "Validate" to check syntax without reformatting.
  3. Copy the result and use it in your config files, documentation, or API testing tools like Postman or cURL.

Common Use Cases for Developers

  • API debugging: Format minified API responses to inspect nested data structures, find specific fields, and understand response shapes.
  • Config file editing: Beautify package.json, tsconfig.json, or other config files for easier manual editing.
  • Log inspection: Format single-line JSON log entries to understand structured logging output from production systems.
  • Documentation: Pretty-print JSON examples for API docs, README files, and developer guides.
  • Payload optimization: Minify JSON before sending as request bodies to reduce bandwidth in high-throughput APIs.

Tips & FAQ

  • Common JSON errors: Trailing commas after the last item, single quotes instead of double quotes, and unquoted property names are the most frequent issues. The validator pinpoints the exact position of syntax errors.
  • JSON vs JavaScript objects: JSON requires double-quoted keys and string values. It doesn't support undefined, functions, comments, or trailing commas — all valid in JavaScript object literals.
  • Privacy guarantee: All formatting and validation happens in your browser using native JSON.parse() and JSON.stringify(). No data is transmitted to any server.