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JSON Toolbox- Free online JSON tools

JSON Formatter

Format JSON online with 2-space, 4-space, or tab indentation. Validation is built in — errors are reported with exact line and column.

  • 100% client-side, nothing uploaded
  • Instant results
  • Works offline once loaded
Input JSON

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Formatted JSON

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How it works

About this tool

This free online JSON formatter reformats your JSON instantly as you type. It validates the input first, so you always know your document is well-formed before using the formatted output in your code, API tests, or documentation.

Choose between 2-space, 4-space, or tab indentation to match your project's style, and enable alphabetical key sorting to produce stable, diff-friendly output. A one-click toggle switches the output to minified JSON when you need a compact payload instead.

Formatting happens entirely client-side using the browser's native JSON engine. There are no uploads, no size limits imposed by a server, and no waiting — even large documents format instantly, and your data stays on your device.

JSON Toolbox processes all data locally in the browser. Nothing is uploaded to a server.

Common questions

Frequently asked questions

How do I format JSON online?
Paste your JSON into the input editor and the formatted version appears instantly in the output panel. Pick your indentation (2 spaces, 4 spaces, or tabs), optionally sort keys, then copy or download the formatted JSON.
Does this JSON formatter also validate my JSON?
Yes. The formatter parses your input first, so invalid JSON is detected immediately with the exact line and column of the error. Only valid JSON is formatted, which guarantees the output is always well-formed.
What indentation should I use for JSON?
Two spaces is the most common convention for JSON in web projects and matches the default output of most tools. Four spaces improves readability for deeply nested documents, and tabs let each developer control the display width in their own editor.
Is this online JSON formatter free and private?
Yes. It is completely free with no limits, and formatting runs entirely in your browser. Your JSON is never uploaded or stored, so it is safe for sensitive payloads.

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