JSON Formatter & Validator
Paste your JSON to format, beautify, minify, or validate it. Errors are reported with approximate line and column information.
How to use this tool
- Paste your JSON into the input area, or click Load Sample.
- Click Format / Beautify to pretty-print with indentation.
- Click Minify to compress to a single line.
- Click Validate to check if the JSON is valid.
- Click Copy Output to copy the result.
This tool uses the browser's built-in JSON.parse() and JSON.stringify(). Input is never executed as JavaScript — it is only parsed as data. No JSON content is sent to an external server.
JSON Syntax Standards (RFC 8259) and Debugging Guide
JavaScript Object Notation (JSON) is the universal data interchange format for modern REST APIs, GraphQL endpoints, and configuration files. Validating syntax before deploying API payloads prevents silent application crashes:
| Syntax Rule | Invalid Example | Valid Example |
|---|---|---|
| String Quotes | {'name': 'Alex'} |
{"name": "Alex"} |
| Trailing Commas | [1, 2, 3,] |
[1, 2, 3] |
| Unquoted Keys | {status: true} |
{"status": true} |
| Values Supported | undefined, NaN, Function |
string, number, object, array, boolean, null |
Line and Column Error Localization
When validation fails, our parser catches the syntax exception and displays the exact line and position where the formatting error originated, speeding up JSON debugging for developers.
Frequently asked questions
In standard JSON (RFC 8259), keys and string values must use double quotes (`"`), not single quotes (`'`). Other common causes include trailing commas after the last array or object element, unescaped backslashes, and unquoted identifiers.
Beautifying adds newlines and consistent indentations (2 or 4 spaces) to make JSON human-readable for debugging. Minifying strips all unnecessary whitespace and carriage returns, reducing payload size for faster HTTP network transmission.
Yes. The validator recursively parses unlimited nesting levels of JSON objects, arrays, booleans, strings, numbers, and null literals.
Never. Unlike online services that log API payloads, BrightKit validates JSON in the browser's JavaScript V8/SpiderMonkey engine without making any remote network calls.
No. The official JSON specification (RFC 8259) does not allow single-line (`//`) or multi-line (`/* */`) comments. Comments must be removed before JSON can parse successfully.