JSON (JavaScript Object Notation) is the most widely used format for exchanging data between applications, APIs, and web services. If you have ever copied a response from an API or opened a config file, you have seen JSON. This tool helps you read, clean, and validate it instantly.
{"{ }"} or square bracket [ ]// like this) โ JSON does not support commentsYour JSON data is processed entirely in your browser. Nothing is sent to any server. This is safe to use with API responses, configuration files, and any sensitive data.
JSON (JavaScript Object Notation) is a lightweight data format used to exchange data between servers and web applications. Unformatted JSON is often minified (all on one line) to save bandwidth. A JSON formatter adds indentation and line breaks to make it human-readable and easy to debug.
Paste your JSON into this formatter and click Format. If the JSON is invalid, you will see an error message pointing to where the syntax error is. Common JSON errors include missing commas, unquoted keys, trailing commas, and using single quotes instead of double quotes.
Standard JSON requires double-quoted string keys, no trailing commas, and no comments. JSON5 is a superset that allows single quotes, trailing commas, comments, and unquoted keys. JSON5 is more human-friendly but not universally supported. Most APIs and web services use standard JSON.
JSON arrays of objects can be converted to a table or CSV format. Each object becomes a row and each key becomes a column. This JSON formatter focuses on formatting and validation. For JSON to CSV conversion, use a dedicated online JSON-to-CSV tool.
This browser-based JSON formatter can handle most real-world JSON files. Very large JSON files (10 MB+) may be slow to format due to browser memory limits. For very large files, a desktop editor like VS Code with the Prettier extension is recommended.
Unformatted JSON is typically minified into a single line to reduce file size during transmission between servers and clients. While this is efficient for machines, it is nearly impossible for humans to read or debug. A JSON formatter adds indentation, line breaks, and consistent spacing so that the structure of the data becomes immediately visible. This is essential during API development, where you need to inspect response payloads quickly. It is equally valuable when debugging configuration files, reviewing webhook data, or collaborating with teammates who need to understand a data structure at a glance. Formatted JSON also makes it much easier to spot errors such as missing brackets, misplaced commas, or incorrect nesting that would be invisible in a minified string.
JSON follows a strict set of syntax rules that every developer should know. Data is organised into key-value pairs, where keys must always be strings enclosed in double quotes. Values can be strings, numbers, booleans, null, arrays, or nested objects. Arrays are ordered lists enclosed in square brackets, while objects are unordered collections enclosed in curly braces. Objects and arrays can be nested to any depth, allowing complex data structures. The most common JSON errors include using single quotes instead of double quotes, adding a trailing comma after the last item in an array or object, including comments which are not supported in standard JSON, and forgetting to close a bracket or brace. This JSON formatter will catch all of these mistakes and point you to the exact location of the error so you can fix it quickly.