Online JSON Formatter

Free online JSON formatter and beautifier

A JSON formatter turns compact or inconsistently indented JSON into a readable structure. This online JSON beautifier uses standard parsing and stringification, and supports objects, arrays, strings, numbers, booleans and null values. See the number precision and duplicate-key limitations below. Choose two spaces, four spaces or tabs, and optionally sort object keys for easier comparison.

How to format JSON online

1. Paste JSON into the input editor or upload a .json file up to 5 MB.
2. Select your indentation and decide whether object keys should be sorted.
3. Choose Format JSON for a pretty print, Validate for a syntax check or Minify for compact output.
4. Copy the result or download it as a new JSON file.

JSON validator for common syntax problems

Valid JSON requires double-quoted property names and strings, balanced braces and brackets, and commas between neighbouring values. Trailing commas, comments, single-quoted strings, undefined and unquoted keys are valid in some JavaScript contexts but are not valid JSON. This checker reports parsing errors rather than silently changing your data.

JSON formatting example: before and after

A compact API response is easier to inspect with consistent indentation. Paste this example into the editor above or choose Sample to try the controls.

Before: compact JSON

{"name":"Esperto","active":true,"tools":["formatter","validator"]}

After: JSON with two-space indentation

{
  "name": "Esperto",
  "active": true,
  "tools": [
    "formatter",
    "validator"
  ]
}

Fix common JSON errors

• Property names: use double quotes, such as {"name":"Esperto"}, rather than unquoted keys or single quotes.
• Trailing commas: remove the comma after the final item in an object or array.
• Comments and JavaScript: remove comments, variable declarations and values such as undefined. This tool accepts strict JSON, not JSON5 or JavaScript code.
• API responses: paste the JSON body alone. An HTML error page or HTTP response headers cannot be formatted as JSON.

Supported features and limitations

Choose two spaces, four spaces or tabs; optionally sort object keys; validate syntax; minify; and copy or download the result. File uploads support .json files up to 5 MB. Validation checks JSON syntax, rather than whether the data matches a JSON Schema or a business rule.

This formatter uses JavaScript’s JSON parser. Integers outside the safe range (−9,007,199,254,740,991 to 9,007,199,254,740,991) can lose precision; store large identifiers as quoted strings. Duplicate property names keep their last value. Formatting can normalize number notation and escape sequences, so keep a copy of the original when exact text matters.

Related JSON and developer tools

• JSON Diff Checker — compare two JSON documents to inspect added, removed and changed values.
• YAML to JSON Converter — convert YAML before formatting it as JSON.
• JSON Schema Generator — create a starting schema from sample JSON.
• JWT Decoder — inspect a token’s JSON header and payload; decoding does not verify its signature.

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