JSON formatter & validator
Beautify, minify, and validate JSON, in your browser.
Invalid JSON:
✓ Valid JSON
This JSON formatter takes messy or minified JSON and reformats it with clean indentation so it is easy to read and review. Acting as a JSON validator at the same time, it parses your input and points out syntax problems like trailing commas, unquoted keys, or mismatched brackets so you can fix them quickly. You can also collapse formatted JSON back into a compact single line when you need to paste it into a config or request body. All parsing happens in your browser, so even private payloads stay on your machine.
Frequently asked questions
What counts as invalid JSON?
Common culprits are trailing commas, single quotes, comments, and unquoted keys, none of which the JSON standard allows. The validator highlights where parsing fails.
What's the difference between beautify and minify?
Beautify adds indentation and line breaks for readability, while minify strips whitespace to make the smallest possible output for transmission.
Is my data uploaded to validate it?
No. Formatting and validation run entirely client-side, so your JSON never leaves the browser.
Does JSON allow comments?
No. The JSON standard has no comment syntax, so // or /* */ make a document invalid. Variants like JSONC or JSON5 add comments, but standard parsers reject them.
What's the difference between JSON and a JavaScript object?
JSON is a strict text format requiring double-quoted keys and no trailing commas, while a JS object literal is looser. All JSON is valid-ish JS, but not every JS object is valid JSON.
How should I handle very large JSON files?
In-browser formatting is fine for typical payloads, but multi-megabyte files can be slow or memory-heavy. For huge data, stream it with a tool built for large files rather than formatting it whole.
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