How to Format and Validate JSON Online

JSON is a text format used to exchange structured data between applications and services. Minified JSON can be difficult to read, while incorrectly written JSON may fail to parse. A formatter makes the structure easier to inspect and can help identify syntax errors.

Open JSON Formatter →

What does a JSON formatter do?

A JSON formatter parses JSON text and displays it with indentation and line breaks. A validator checks whether the input follows JSON syntax. A minifier removes unnecessary whitespace to make valid JSON more compact. Formatting changes presentation; it does not automatically correct every data or application-level problem.

Format JSON with ToolNovus

1. Open the ToolNovus JSON Formatter. 2. Paste your JSON text into the input area. 3. Use the format or beautify action to make the structure easier to read. 4. If the tool reports an error, review the indicated position and correct the source. 5. Copy or download the result if those controls are available. Test the JSON in the application that will consume it.

Common JSON syntax errors

JSON requires double quotes around property names and string values. Commas separate items, but a trailing comma after the last item is not valid JSON. Objects use curly braces and arrays use square brackets. Values can include strings, numbers, booleans, null, objects and arrays. Comments are not part of standard JSON syntax.

Example of valid JSON

{
  "name": "ToolNovus",
  "free": true,
  "tools": ["image", "pdf", "text"]
}

In this example, property names and string values use double quotes, the boolean value is unquoted, and array items are separated by commas. Your actual data can contain nested objects and arrays.

Formatting does not guarantee data safety

Do not paste passwords, API keys, access tokens, private customer records or other secrets into an online formatter. Even when parsing occurs in the browser, the page may load analytics and third-party resources. Remove or replace sensitive values before using a web-based utility. Also remember that syntactically valid JSON can still contain incorrect values or fail an application’s schema rules.

Related tool: JSON Formatter. Review the output before using it for an important submission or decision.

Frequently asked questions

Does formatting JSON change its data?

A formatter should change whitespace and indentation, not the meaning of valid JSON. Still, compare important output and test it in the target application.

Why does JSON reject single quotes?

Standard JSON strings and property names must use double quotes.

Can JSON contain comments?

Standard JSON does not support comments. Remove comments or use a different format if your workflow requires them.

What is minified JSON?

Minified JSON removes unnecessary whitespace and line breaks, making the text shorter but harder for people to read.

Last reviewed: October 31, 2026. Tool interfaces and supported formats may change; follow the current instructions shown on the tool page.