JSON Formatter & Validator
Instantly format, pretty-print, and validate JSON. Detects syntax errors with position info, and shows key count, max depth, and byte size.
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Frequently asked questions
What is JSON?
JSON (JavaScript Object Notation) is a lightweight text format for storing and transmitting structured data. It supports 6 data types: strings (double-quoted), numbers, booleans (true/false), null, arrays (ordered lists in []), and objects (key-value pairs in {}). It is the de facto standard for REST API responses and configuration files.
What are common JSON syntax errors?
The most frequent mistakes: (1) Trailing commas after the last item in an object or array — valid in JavaScript but banned in JSON. (2) Single quotes around strings — JSON requires double quotes. (3) Unquoted property keys — {"name": "John"} is correct. (4) Missing comma between properties. (5) Comments — JSON has no comment syntax. (6) NaN and Infinity — not valid JSON values.
What is the difference between JSON and XML?
Both are human-readable data interchange formats. JSON is more concise, natively maps to JavaScript/Python data structures, and is used in virtually all modern APIs. XML is more verbose but supports schemas (XSD), namespaces, mixed content, attributes, and XSLT — still common in enterprise systems, SOAP APIs, and document formats like Word (.docx) and SVG.