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JSON Formatter & Validator

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Working with APIs and config files often means wrestling with minified or invalid JSON. This free JSON formatter beautifies or minifies your JSON and validates it with clear error messages.

Paste raw JSON, format it with indentation, compress it to a single line, or check whether it parses correctly. Everything stays on your device — useful when dealing with sensitive payloads.

No accounts, no server upload. Ideal for developers, QA and anyone debugging web services.

Interactive tool

How to use this tool

  1. Paste or type JSON into the input area.
  2. Click Format to pretty-print, or Minify to compress.
  3. Use Validate to check for syntax errors without changing layout.
  4. Copy the result with the copy button when ready.

Why validate JSON locally?

API payloads and config files often break because of a trailing comma, single quotes, or a comment that strict JSON does not allow. Validating in the browser means you never paste secrets into an unknown third-party server.

Pretty-printing with consistent indentation makes code review and diffing easier; minifying reduces size for transport. This tool uses the browser’s built-in JSON.parse and JSON.stringify.

Frequently asked questions

Is my JSON uploaded to a server?
No. Parsing and formatting use the browser’s JSON.parse / JSON.stringify only.
What counts as valid JSON?
Strict JSON: double-quoted keys and strings, no trailing commas, no comments, and supported value types (object, array, string, number, boolean, null).
Can it fix invalid JSON automatically?
No. It reports parse errors so you can correct the source. Auto-repair of broken JSON is intentionally not attempted.
What indent size is used when formatting?
Two spaces by default, which is a common convention for readability.

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