Developer tools
JSON Formatter, Validator & Minifier
Make JSON readable, check its syntax or remove unnecessary whitespace. Paste a document, choose an action and copy or download the result without uploading it.
Inputs are processed on your device. No account required.
Format, validate or minify
Formatting parses the document and writes it with two or four spaces per indentation level. Minifying writes the same parsed data without formatting whitespace. Validation checks JSON syntax and reports the parser error without replacing your input. Strings need double quotes; trailing commas and JavaScript comments are not valid JSON.
A result is not a JSON Schema validation or proof that an API will accept the document. This uses the browser’s JavaScript JSON parser. Duplicate keys follow that parser’s last-value behaviour. Large integer values outside JavaScript’s safe range are rejected to prevent silent identifier changes; quote those identifiers as strings. Decimal values follow JavaScript floating-point precision.
The 2 MB limit keeps routine formatting responsive on phones and laptops. Inputs are not saved by this widget. Downloads are created on your device; ordinary website hosting and existing site services remain separate from calculator processing.
Frequently asked questions
Will formatting execute the JSON?
No. The tool uses JSON.parse and JSON.stringify; it does not evaluate pasted JavaScript.
Why was a large numeric identifier rejected?
JavaScript numbers cannot represent every large integer exactly. Quoted identifiers remain strings and avoid accidental rounding.
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