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JSON Formatter

Format, validate and minify JSON - fully client-side

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JSON Formatter

Indent:

What this tool does

Pretty-prints and validates JSON. Minifies back to a single line when needed. Highlights syntax errors with line numbers. Runs client-side.

Who it's for: Developers inspecting API responses, log analysts reading JSON logs, and anyone struggling to read compressed JSON in the wild.

When to use

  • •Format a compressed JSON API response into something readable.
  • •Validate that user-submitted JSON is syntactically correct.
  • •Minify JSON for embedding in a URL or request body.
  • •Spot missing commas, unclosed brackets, or trailing commas.

How it works

  1. 1Paste JSON into the input area.
  2. 2Pretty-print with 2-space indent or minify to one line.
  3. 3Errors highlight exactly where the syntax breaks.
  4. 4All parsing is done by the browser's native JSON engine.

Tips

  • •Trailing commas are invalid in strict JSON - different from JavaScript.
  • •Keys MUST be double-quoted; single quotes or unquoted keys fail.
  • •Use JSON Schema for runtime validation, not just format-checking.

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