Pretty-print, minify, and validate JSON data with syntax highlighting. Paste your JSON below to format it instantly -- everything runs in your browser.
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Get Started FreeJSON (JavaScript Object Notation) is a lightweight, text-based data interchange format that is easy for both humans and machines to read and write. Defined in RFC 8259, JSON is language-independent and supported by virtually every programming language. It uses two main structures: objects (unordered collections of key-value pairs enclosed in curly braces) and arrays (ordered lists of values enclosed in square brackets). JSON supports six data types: strings (always double-quoted), numbers, booleans (true/false), null, objects, and arrays. Its simplicity and universality have made it the standard format for REST APIs, configuration files, and front-end/back-end data exchange.
When working with JSON, several common mistakes cause parsing failures. Trailing commas after the last element in an array or object are not allowed -- unlike JavaScript, JSON is strict about this. Single quotes are invalid; JSON requires double quotes for all strings and keys. Unquoted keys will cause a parse error since every key must be a double-quoted string. Comments of any kind (// or /* */) are not part of the JSON specification. JavaScript-specific values like undefined, NaN, and Infinity are also invalid in JSON. This formatter and validator will catch all of these errors and help you identify the exact line where the problem occurs.
JSON has largely replaced XML as the preferred format for modern web APIs. JSON is more compact, typically 30-50% smaller than equivalent XML representations, which reduces bandwidth usage and parsing time. Most programming languages can parse JSON natively without external libraries. XML, however, still has advantages in enterprise contexts: it supports schemas (XSD) for strict validation, namespaces for avoiding element name conflicts, and XSLT for document transformation. For new REST API projects, JSON is almost always the right choice. For SOAP services, document-centric applications, and systems requiring strict schema validation, XML remains relevant. This tool helps you debug and format JSON responses from APIs, making it easier to inspect payloads during development.