Free JSON Formatter: Validate & Format with 2 or 4 Spaces

KHIYALEE / FREE DEVELOPER TOOLS

JSON formatter: Paste JSON to check its syntax and create a readable or compact version. Choose two-space or four-space indentation, or remove optional formatting whitespace. This tool supports standard JSON values and displays the browser’s parsing error when the input is not valid.

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How to use the JSON formatter

1. Paste a small JSON document into the input box.
2. Choose two spaces, four spaces or compact output.
3. Select Format JSON and read any error before copying.
4. Compare the formatted values with your original document.

Worked example

The valid input {"name":"Khiyalee","active":true,"items":[1,2]} can be expanded onto several indented lines. A trailing comma after the final property is invalid JSON and must be removed.

JSON Formatter & Validator: understand the result

Formatting and validation are different

Formatting changes indentation and line breaks so that a person can follow nested objects and arrays. Validation here checks JSON syntax with the browser’s parser. It does not confirm an API schema, required fields, business rules or whether an email address inside a string is correct. A syntactically valid document can still be rejected by an application.

Frequent syntax mistakes

Use double quotes around property names and string values. Remove trailing commas and comments. The values true, false and null use lowercase letters and are not quoted. A missing colon or closing bracket can cause a parsing error. The message points to a problem area, but the exact wording depends on your browser.

Precision and duplicate-key limitations

JavaScript represents most numbers as floating-point values. Very large integers can lose precision when parsed and rewritten, so keep identifiers that must remain exact as strings. If an object repeats a property name, only the final value survives this parser. Save an original copy before formatting a configuration, and do not treat the formatter as a lossless archival tool.

Use the JSON formatter on mobile or desktop

The JSON formatter controls adapt to the available screen width. On a phone, fields stack vertically; on a wider screen they stay grouped together. Choose the mode first, read the input labels, and then generate the result. The Copy result button copies the output if your browser allows clipboard access. If permission is unavailable, the output is selected so that you can copy it manually.

Keep a copy of any important input in your own document before resetting or leaving the page. Reset restores the starting controls and clears the displayed output; it does not create an undo history. The tool does not retain previous results, compare them with a database or submit them to another application for you.

After copying, check the result in the destination where you intend to use it. Preserve meaningful units, labels and exact characters. A browser calculation or conversion can be correct while a separate form, document or production process expects a different input format. Use the example above to understand the operation before relying on your own result.

JSON Formatter & Validator: frequently asked questions

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Reference: MDN JSON parsing reference. Examples are illustrative; use your own inputs for the final result.