How to Format and Validate JSON Online

Quick answer

Paste JSON into the OnlineBox JSON Formatter and Validator to format, validate and minify it in your browser. The tool checks syntax as you type and helps identify common JSON errors before you use the data in an API, config file or webhook.

How to format JSON

1. Open the JSON Formatter.
2. Paste raw JSON into the input area.
3. Click Format to beautify it with indentation.
4. Click Minify if you need a compact one-line version.
5. Use Copy result when the output is ready.

Common JSON validation errors

JSON is stricter than JavaScript object syntax. Keys must use double quotes, string values must use double quotes, comments are not allowed and trailing commas are invalid.

For example, this is not valid JSON:

{
  name: "OnlineBox",
}

This is valid:

{
  "name": "OnlineBox"
}

When to use an online JSON formatter

Use it for API responses, webhook payloads, configuration files, mock data, browser localStorage values and debugging snippets. If you are preparing tabular data for an API, you can also use the CSV to JSON converter.

FAQ

Does my JSON upload to a server?

No. Formatting and validation run in your browser.

Can it show the error line?

When the browser parser provides enough detail, the tool converts the error position into line and column information.

What is minified JSON?

Minified JSON removes extra spaces and line breaks. It is useful for storage, URLs and compact API payloads.