Free Online JSON Formatter & Validator

Use this free online JSON formatter to make compact or hard-to-read JSON easier to inspect. Paste JSON to format or beautify it with two-space, four-space, or tab indentation, validate its syntax, inspect a read-only tree, or minify it for a compact copy. This JSON formatting tool runs in your browser; the text you enter is not sent to our server.

What this JSON formatter and validator does

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• Format and beautify JSON: pretty print valid JSON as consistently indented, readable output.
• Choose JSON indentation: use two spaces, four spaces, or tabs for nested objects and arrays. Your choice is saved as a browser preference; the JSON itself is not saved.
• Validate JSON syntax: use the browser’s JSON parser to check input and show its syntax error when it cannot be parsed.
• Minify JSON: remove formatting whitespace from valid JSON.
• Review a limited repair: preview removal of trailing commas only when the change makes the full input valid. Applying it writes a result while leaving the source input unchanged.
• Inspect structure and statistics: expand a bounded, read-only tree or review counts for values, properties, arrays, depth, and size.
• Open a local file: browse for or drop a UTF-8 .json file up to 5 MiB. Files are read in this page, not uploaded.
• Copy or download: copy the result or save it as formatted.json.

Use it as an online JSON code formatter, beautifier, syntax checker, minifier, and read-only JSON tree viewer. The input remains editable raw JSON text, not a structured tree editor. The repair assistant suggests only unambiguous trailing-comma removal; it does not repair other syntax errors or fetch JSON from a URL. Tree and statistics views use the browser’s native number representation, so very large or high-precision numeric values should be checked in the source text; formatting and minifying preserve the original number tokens.

Format JSON online for free

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1. Paste or type JSON into Your JSON, or select Load sample to try an example.
2. Choose two spaces, four spaces, or tabs.
3. Select Format JSON to beautify or pretty print JSON, Validate to check syntax, or Minify for compact output.
4. Copy the result or download it as a JSON file.

Your input and result stay in the current page. Use Clear to remove both. On mobile, use the Input and Output tabs to switch editor panes. The Tree and Statistics tabs are generated only when opened.

Format JSON with two or four spaces

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The JSON formatter with indentation offers two-space, four-space, and tab options for nested objects and arrays. Choose the style your project uses, then format the JSON again. Formatting and minifying change whitespace only and preserve the original JSON tokens, including large numeric literals.

Explore JSON structure and statistics

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Open Tree after entering valid JSON to expand or collapse nested objects and arrays. The tree is read-only and capped at 1,000 rendered nodes, with at most 100 direct children rendered for one expanded value. The cap prevents a very wide or deep input from creating an unbounded page. Use the code view for the complete document.

Open Statistics to count objects, arrays, properties, array elements, scalar values, and maximum depth. Input size is measured as UTF-8 bytes; compact serialized size is the size of the browser-parsed representation. Depth starts at zero for the root. Statistics and tree values rely on JavaScript’s native number type, unlike the formatter’s token-preserving output.

JSON formatting example

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Compact JSON:

{"user":{"name":"Ari","active":true},"roles":["editor","admin"]}

Formatted with two spaces:

{
  "user": {
    "name": "Ari",
    "active": true
  },
  "roles": [
    "editor",
    "admin"
  ]
}

Formatting changes whitespace, not the JSON data. Minifying produces a compact representation of the same parsed value.

Validate JSON syntax and fix common errors

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JSON is stricter than JavaScript object-literal syntax. If validation fails, check for:

• Single quotes: JSON strings and property names use double quotes, such as "name": "Ari".
• Unquoted property names: write "active": true, not active: true.
• Trailing commas: remove the comma after the last item in an object or array.
• Comments: standard JSON does not allow // or /* ... */ comments.
• Missing separators or brackets: match every opening { or [ and separate members with commas.

The exact diagnostic wording depends on the browser. When the browser supplies a reliable numeric offset, the tool shows its line, column, and nearby source context; otherwise it displays no invented position. For a trailing comma only, choose Review repair to inspect a proposed result. Other errors must be corrected in the source by you.

Open a JSON file privately

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Choose Open .json file or drop a file into the file area. The tool accepts UTF-8 files up to 5 MiB and reads them locally. Invalid JSON is still loaded so you can inspect and edit it; a file that exceeds the limit or cannot be decoded as UTF-8 leaves the current input untouched. Formatting, validation, repair previews, the tree, and statistics do not send JSON to a server.

Keyboard shortcuts

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When focus is inside the workspace, use Ctrl + Enter to format, Ctrl + Shift + M to minify, or Ctrl + Shift + C to copy the result. On macOS, use Command instead of Ctrl.

Frequently asked questions

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How do I format JSON online for free?

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Paste valid JSON into the input, choose two or four spaces, and select Format JSON. This online JSON formatter creates a readable result beside the input on desktop and below it on smaller screens.

How can I check whether JSON is valid?

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Paste it into the input and select Validate. The page reports whether the browser can parse it as JSON. If it is invalid, review the syntax message and check common issues such as single quotes, comments, or trailing commas.

Can I choose the JSON indentation?

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Yes. Choose two spaces, four spaces, or tabs before formatting. The selector can also reformat an existing valid output, and your indentation preference is stored in this browser.

Is this a JSON viewer or an online JSON editor?

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The Tree tab provides a read-only, bounded view of nested JSON. You can edit raw JSON text in the code input, but the tree does not provide structured editing or syntax highlighting.

Does this work as an online JSON parser?

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The browser’s built-in JSON parser checks whether the input is valid and the formatter serializes valid data as readable or minified JSON. It is not a general-purpose converter or remote URL parser.

Does this JSON formatter upload or save my input?

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No. Formatting, validation, and minification run locally in your browser. The tool does not upload or save the input.

Can it repair invalid JSON?

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Only a narrow case is supported: the repair assistant can preview removal of trailing commas when the complete result then parses as valid JSON. You must review and explicitly apply the suggestion; it is written to the output, and the original input remains unchanged. Other syntax errors are not repaired.

Does this formatter change numeric values?

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Formatting and minifying preserve the source number tokens and only change whitespace. The Tree and Statistics tabs parse JSON with the browser’s native JavaScript number type, which cannot represent every possible JSON number exactly.

What is the difference between formatting and minifying JSON?

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Formatting adds indentation and line breaks to make JSON easier to read. Minifying removes unnecessary whitespace to make the serialized JSON more compact.

Explore more developer tools

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Browse the Developer Tools collection or return to the AR Tech Finder tools directory to find other browser-based utilities as they become available.