Format, validate, beautify and minify JSON data.
JSON (JavaScript Object Notation) is the lingua franca of web APIs, configuration files, and structured data exchange. A correctly formatted JSON document is also a strict syntactic specification, and small errors (missing comma, trailing comma, unquoted key) can break entire pipelines. Our JSON formatter beautifies, minifies, and validates JSON without leaving your browser.
Beautifying JSON adds whitespace and line breaks so a human can read nested structures. Minifying JSON removes all unnecessary whitespace to reduce payload size. Validation confirms that the input follows the JSON grammar: matched braces and brackets, double-quoted keys, no trailing commas, escaped strings.
Paste raw JSON into the input box, choose Beautify or Minify, and the formatted output appears. If the input contains a syntax error the tool highlights the location and shows a friendly message so you can fix it. All processing is local; your JSON is never sent over the network.
Use double quotes for keys and string values — single quotes are not valid JSON. Avoid trailing commas after the last item in arrays and objects. Use ISO 8601 strings or Unix timestamps for dates. For large documents prefer a streaming parser in your application rather than loading the whole structure into memory at once.
No. JSON is a strict subset of JavaScript syntax. Real JavaScript allows trailing commas, unquoted keys, single quotes, and comments — JSON does not.
Standard JSON does not allow comments. If you need comments use a superset format such as JSON5 or JSONC.
There is no enforced size limit beyond your browser memory. Documents of several megabytes are handled comfortably in modern browsers.
