toolboxapp

JSON Formatter

Paste minified or compact JSON and get it back formatted with proper indentation — readable, debuggable and validated.

Minified JSON is compact and efficient to transmit, but nearly impossible to read or debug by eye. This tool reformats any JSON with consistent two-space indentation, making it easy to inspect keys, trace nested structures and understand the shape of the data. It also validates the JSON as part of the formatting process — if the input has a syntax error, the tool reports it clearly instead of producing incorrect output.
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Data Tools

Runs locally  ·  No data sent to server  ·  Free, no signup

About JSON Formatter

Minified JSON is compact and efficient to transmit, but nearly impossible to read or debug by eye. This tool reformats any JSON with consistent two-space indentation, making it easy to inspect keys, trace nested structures and understand the shape of the data. It also validates the JSON as part of the formatting process — if the input has a syntax error, the tool reports it clearly instead of producing incorrect output.

How to use JSON Formatter

Paste your minified, compact or raw JSON into the input box and click Run. The formatter parses and re-serialises the JSON with two-space indentation. If the JSON is valid, the formatted result appears instantly. If there is a syntax error — a missing quote, trailing comma, unmatched bracket — an error message identifies the problem.

When to use this tool

Use this when you receive a minified API response and need to inspect its contents, when reviewing JSON config files or environment settings, when debugging a payload sent to or received from a REST or GraphQL API, when preparing JSON to share with a colleague, or any time compact JSON needs to be made readable.

Privacy

Formatted JSON is dramatically easier to debug, review and share than compact JSON. Whether you are inspecting an API response, reviewing configuration, reading a log file or sharing a data structure with a colleague, proper indentation makes the structure immediately readable. All processing runs in your browser — no JSON is sent to a server.

Frequently asked questions

Does this tool validate JSON as well as format it?

Yes. The tool parses the input as strict JSON before formatting. If the input has a syntax error — such as a missing quote, a trailing comma after the last item, a single-quoted string or an unmatched bracket — the tool reports an error rather than outputting malformed content.

What indentation does it use?

Two-space indentation, which is the most widely used convention for JSON and is consistent with most style guides, linters and code editors.

My JSON is valid but the formatter shows an error. Why?

JSON is stricter than most people expect. Common causes: trailing commas after the last property or array item (not valid in JSON), single-quoted strings (JSON requires double quotes), unquoted property keys, and comments (JSON does not support comments). If your JSON came from a JavaScript file or config, try the Fix Invalid JSON tool instead.

Can I format very large JSON responses?

Yes, within browser memory limits. Files up to several megabytes format without issues. Very large files may take a moment depending on your device, but there are no server-side size restrictions.