What is JSON Formatter?

JSON Formatter is a tool for making JSON strings easier to read while also helping you check for syntax errors. It is useful when you want to inspect an API response, tidy up a config file, or quickly verify whether pasted JSON is valid.

The tool formats the input automatically and shows an error message when the JSON cannot be parsed. It works well for quick browser-based checks during debugging or data inspection.

How to Use

1. Paste a JSON string into the input area.
2. Review the formatted output.
3. Change the indentation style or space width if needed.
4. If an error appears, fix the highlighted issue and check again.

Because the output updates with the input, it is easy to compare different formatting styles as you work.

Main Settings

Indent Style

You can choose from three output styles:

• Spaces: A common and readable formatting style
• Tabs: Useful when your project prefers tab-based indentation
• None: Removes line breaks and indentation when you want a compact output

If readability is the goal, spaces or tabs are usually the better choice. If you want to reduce the size before sending JSON somewhere, None is more useful.

Indent Spaces

When you use spaces, you can choose 2 / 4 / 6 / 8 as the indentation width. In most cases, 2 or 4 is the easiest choice, depending on your project's formatting rules.

Use Cases

• Inspecting API responses in a readable format
• Tidying config files or example JSON data
• Expanding minified JSON back into something readable
• Doing a quick syntax check before using JSON elsewhere

What to Check When an Error Appears

• Whether strings use double quotes
• Whether there is an extra trailing comma
• Whether an object or array is missing a closing bracket
• Whether keys and values are separated correctly with a colon

This tool mainly helps with syntax problems. It does not tell you whether the values themselves make sense for a specific API or schema, so that part still needs to be checked separately.

Input and Output Example

{ "name": "Taro Tanaka", "age": 30, "hobbies": ["reading", "traveling"] }

When you paste a one-line JSON string like this, the tool reformats it as:

{
  "name": "Taro Tanaka",
  "age": 30,
  "hobbies": [
    "reading",
    "traveling"
  ]
}