Paste JSON to pretty print, minify, or validate. Everything runs in your browser.
JSON (JavaScript Object Notation) is a lightweight data format used to store and exchange data. It is the standard format for APIs, configuration files, and data transfer between web applications. JSON is human-readable when properly formatted but often arrives as a single minified line that is difficult to read. This tool formats (or "prettifies") JSON for readability and validates that the syntax is correct.
Paste raw JSON into the input field. The formatter instantly validates the syntax (showing any errors with line numbers), adds proper indentation and line breaks, and highlights the structure with syntax coloring. You can also minify formatted JSON (remove all whitespace) to reduce file size for transmission, and copy the result to your clipboard.
Missing comma: The most common error. Every key-value pair in an object and every element in an array must be separated by a comma (except the last one). Trailing comma: JSON does not allow a comma after the last element, unlike JavaScript. Single quotes: JSON requires double quotes for strings. Single quotes are invalid. Unquoted keys: All keys must be double-quoted strings. These are easy mistakes that the formatter highlights instantly.
JSON (JavaScript Object Notation) is the dominant data interchange format on the modern web, used by virtually every API, configuration system, and data pipeline. JSON supports six data types: strings (in double quotes), numbers (integer or floating point), booleans (true/false), null, arrays (ordered lists in square brackets), and objects (key-value pairs in curly braces). Its simplicity and readability made it the successor to XML for most web applications.
Common JSON issues include: trailing commas (not allowed in standard JSON despite being valid in JavaScript), single quotes (JSON requires double quotes), unquoted keys (all keys must be strings in double quotes), and comments (not supported in standard JSON). These are the most frequent syntax errors that cause parsing failures. JSON5 is an extension that relaxes some of these rules, but standard JSON remains the interchange format expected by most APIs.
Minified JSON (all whitespace removed) reduces file size for network transmission but is nearly impossible to read. This formatter adds consistent indentation (typically 2 or 4 spaces) and line breaks to make the structure visible. For large JSON files, tools like jq (command-line), JSONPath (query language), and browser developer tools provide search, filter, and transform capabilities. Validating JSON before sending it to an API prevents cryptic parsing errors on the server side. The Password Generator and QR Code Generator are other developer-adjacent tools on this site.
JSON has become the backbone of modern web development. REST APIs return JSON by default, configuration files for tools like npm (package.json), VS Code (settings.json), and TypeScript (tsconfig.json) all use JSON. NoSQL databases like MongoDB store documents as BSON (Binary JSON). Even data interchange between microservices predominantly uses JSON over alternatives like Protocol Buffers and MessagePack, though those binary formats offer better performance for high-throughput systems. Understanding JSON structure and being able to quickly format, validate, and debug JSON payloads is an essential skill for web developers, QA engineers, and anyone working with APIs or modern data systems.
JSON (JavaScript Object Notation) has become the dominant data interchange format for web APIs, configuration files, and data storage. Key best practices include: use consistent naming conventions (camelCase is most common in JavaScript contexts, snake_case in Python/Ruby), keep nesting depth below 3 to 4 levels for readability, use arrays for ordered collections and objects for key-value pairs, avoid including sensitive data (passwords, tokens) in JSON logs or error responses. Common debugging issues include trailing commas (invalid in JSON but valid in JavaScript), single quotes instead of double quotes, unescaped special characters in strings, and circular references that cause serialization failures.