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JSON Formatter and Validator

Paste any JSON to pretty-print it with the indentation you want, or minify it to a single line for transport. The validator highlights syntax errors with the exact position the JSON parser fails. Live mode: every keystroke updates the output. Pair it with the CSV to JSON converter when your data starts as a spreadsheet, with the Base64 encoder when you need to embed JSON in a header, or with the regex tester to extract fields once formatted.

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How it works

We feed your input into JSON.parse to validate it, then call JSON.stringify with the requested indent (2 by default) for pretty-print or no indent for minify. Errors come straight from the V8 / SpiderMonkey parser so the position info is accurate.

How to use it

  1. Paste your JSON

    Drop in any JSON value, API response or config snippet. The tool accepts pretty or minified input alike.

  2. Pick indent or minify

    Choose 2 or 4 space indent for human-readable output, or switch to minified to strip every byte of whitespace.

  3. Format and validate

    JSON.parse runs in your tab. If the input is invalid, the parser surfaces the exact line and column of the error.

  4. Copy or download

    One click copies the formatted JSON to your clipboard. Use the download button to save it as a .json file.

Use cases

Pretty-print API responses copied from the network tab.

Minify a JSON config before embedding it in HTML.

Spot a typo or missing comma in hand-written JSON.

Reformat noisy single-line JSON into something readable.

Validate JSON before sending it to a strict endpoint.

When NOT to use it

  • As a schema validator. This tool only checks JSON syntax, not whether your data matches an expected shape. Use Ajv or Zod for that.
  • For huge JSON (above 5 MB). Pretty-printing in the browser will hang. Use jq or a streaming parser.
  • When trailing commas or comments are present. Strict JSON does not accept either. Convert to JSON5 first if your source has them.

Your data never leaves your browser

Every utility runs entirely on your device. Nothing is uploaded, nothing is stored on a server. You can disconnect from the internet and they keep working.

Frequently asked questions

Related tools

Curated next destinations. Use complementary tools in a pipeline; alternatives swap in for a different angle; next-step tools pick up where this one leaves off.

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