Format, validate, and beautify JSON instantly. Pretty print with configurable indentation, syntax highlighting, line numbers, and collapsible tree view. Minify JSON for production use, detect errors with precise line and column reporting, and explore your data structure visually. Free, runs entirely in your browser -- no data ever leaves your machine.
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Format any JSON with configurable indentation -- choose 2 spaces, 4 spaces, or tabs. The output is clean, readable, and ready to copy or download as a .json file.
Validate JSON instantly with precise error reporting. When your JSON is invalid, the tool pinpoints the exact line and column where the error occurs, making it easy to fix syntax issues.
Color-coded output distinguishes keys, strings, numbers, booleans, and null values at a glance. Line numbers make it easy to reference specific parts of your JSON structure.
Explore your JSON as an interactive, collapsible tree. Expand and collapse objects and arrays to navigate deeply nested structures and understand the data hierarchy visually.
JSON (JavaScript Object Notation) is the most widely used data interchange format in modern software development. APIs, configuration files, databases, and messaging systems all rely on JSON to represent structured data. While JSON is easy for machines to parse, raw or minified JSON can be difficult for humans to read and debug. That is where a JSON formatter becomes indispensable.
Formatting JSON -- also called pretty printing or beautifying -- adds proper indentation and line breaks to make the structure visible at a glance. When you are debugging an API response, reviewing a configuration file, or inspecting data from a database, formatted JSON lets you quickly identify nested objects, arrays, missing values, and structural patterns. Minified JSON, on the other hand, removes all unnecessary whitespace to reduce file size for production use, network transfer, and storage.
Paste your JSON into the input pane and click Format to pretty print it with syntax highlighting and line numbers. Click Minify to compress it to a single line. Click Validate to check if the structure is valid JSON. The tool parses your input using the standard JSON specification (RFC 8259) and reports precise error locations when validation fails. Everything runs entirely in your browser -- no data is ever sent to a server.
[1, 2, 3,] is invalid). All strings and object keys must use double quotes -- single quotes are not valid JSON (e.g., {'key': 'value'} is invalid). JavaScript-specific values like undefined, NaN, and Infinity are not valid JSON values. Comments using // or /* */ are not supported. Unquoted object keys, missing colons between keys and values, mismatched brackets or braces, and unescaped special characters in strings (like literal tabs or newlines) will all cause parse errors. Our validator reports the exact location of these errors to help you fix them quickly.
JSON.parse(), you convert a JSON string into a JavaScript object; when you call JSON.stringify(), you convert a JavaScript object into a JSON string (non-serializable values like functions and undefined are omitted).
JSON.parse() method, which strictly follows the JSON specification (RFC 8259). If the JSON is valid, you will see a green success message confirming the structure is well-formed. If it is invalid, you will get a detailed error message indicating what went wrong and, when possible, the exact line and column number where the error was detected. This makes it easy to locate and fix the issue in your original JSON. For programmatic validation, you can use JSON.parse() in JavaScript, json.loads() in Python, or json_decode() in PHP, wrapping the call in a try-catch block to handle errors.
'value' instead of "value", (3) unquoted keys -- writing {key: "value"} instead of {"key": "value"}, (4) JavaScript values -- using undefined, NaN, or Infinity which are not valid JSON, (5) comments -- adding // comment or /* comment */ which JSON does not support, (6) missing commas between elements, (7) mismatched brackets or braces, (8) unescaped control characters in strings (tabs and newlines must be escaped as \t and \n), and (9) duplicate keys which, while technically parsed by most implementations, can lead to unexpected behavior.
// line comments or /* */ block comments in a JSON file, it will fail to parse. However, several JSON-derived formats support comments: JSONC (JSON with Comments) is used by VS Code for its settings files and supports // and /* */ comments; JSON5 extends JSON with comments, trailing commas, single-quoted strings, and more; and YAML, which is a superset of JSON, natively supports comments with the # character. If you need comments in standard JSON files, a common workaround is to use a dedicated key like "_comment" or "//comment" to store comment text as a regular string value, though this adds to the file size.
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