JSON is not a JavaScript object literal
JSON requires double quotes around object keys and string values. Comments, single-quoted strings, undefined, NaN, and Infinity are not valid JSON. The input {"x":1,} is invalid because of the trailing comma; {"x":1} is valid. Check nested brackets and escape quotes inside strings.
Validate, then format or minify
Paste a non-sensitive sample into JSON formatter. Format JSON validates and adds indentation; Minify JSON validates and removes unnecessary whitespace. Invalid input produces an error rather than an automatic repair. Correct the source, run it again, and copy or download the valid result. Formatting does not validate an application-specific schema.
Keep exact identifiers as strings
This tool uses JavaScript JSON parsing. Integers above 9007199254740991 can lose precision, so an identifier such as "9007199254740993" should remain quoted when every digit matters. Formatting cannot recover precision already lost elsewhere. These limits also matter when comparing the result with another programming language.