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What is JSON?

A practical introduction to JSON structure, formatting, validation, and common syntax errors.

The short answer

JSON is a text format for structured data built from objects, arrays, strings, numbers, booleans, and null.

Use the free JSON Formatter

Step by step

  1. Paste JSON into JSON Formatter.
  2. Format it to inspect nesting and indentation.
  3. Read validation errors and correct commas, quotes, brackets, or value types.
  4. Minify only when compact transport is needed.

Technical details

  • JSON requires double-quoted property names and strings. Comments and trailing commas are not part of standard JSON.

Common mistakes

  • Pasting JavaScript object syntax and expecting valid JSON.
  • Treating formatted JSON as schema validation.
  • Putting credentials or personal data into online tools.

Limitations

  • JSON Formatter checks syntax; it does not know whether the data matches an application-specific schema.

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