CodeTools

JSON Formatter

Format and validate JSON · 100% in the browser · no data is sent to the server

Edit the sample or paste an API response, configuration, or test fixture. The content stays in this browser.

Ctrl+Enter / Cmd+Enter
Quick examples
Quick guide and information

How to use

  1. Edit the sample or paste your JSON into the editor.
  2. Click Format (or press Ctrl+Enter).
  3. Review the feedback and copy the formatted result.

The formatter organizes indentation, but it does not change the object's logic, property names, or values.

Features

  • JSON formatting
  • Error identification with line and column
  • Copy the result
  • 100% local processing in the browser

What is JSON?

JSON (JavaScript Object Notation) is a lightweight text format based on key-value pairs. It is widely used to exchange data between APIs and web applications. With the CodeTools JSON Formatter, you organize and validate that data instantly, without sending anything to our servers.

Valid JSON uses double quotes for properties and strings, separates items with commas, and accepts objects, arrays, strings, numbers, booleans, and null. A trailing comma or an unclosed quote usually prevents parsing.

For more detail, see RFC 8259, the formal JSON specification, and the Working with JSON guide on MDN.

Practical cases

  • Inspect a compact API response.
  • Review a configuration before saving it to the repository.
  • Prepare a readable fixture for automated tests.

Limitations

The tool confirms JSON syntax, but it does not check whether the fields make sense for an API or whether the values satisfy your system's rules.

For sensitive data, prefer an installed local tool and review the result before sharing it.

FAQ

What does invalid JSON mean?

It means the text does not follow the syntax expected by the parser. The message includes the line and column when the browser provides that position.

Is the content sent to the server?

No. Formatting and validation happen locally in the browser. Still, avoid entering secrets on any web page.

Does the shortcut work on Linux and macOS?

Yes. Use Ctrl+Enter on Windows/Linux and Cmd+Enter on macOS.