JSON Formatter

Format and Validate JSON Privately

The JSON formatter beautifies, validates, and helps debug JSON data in your browser. It is a safer workflow for API payloads, configuration snippets, and logs that may contain internal data.

JSON Formatter vs JSON Validator

Formatting makes JSON easier to read with indentation and line breaks, while validation checks whether the structure is valid. This tool supports both workflows so developers can inspect data faster.

Common Developer Use Cases

Use the formatter when reviewing API responses, cleaning minified JSON, preparing examples for documentation, or locating syntax errors before pasting data into code or test fixtures.

How this tool works

The formatter parses input with the browser's JSON parser and serializes the resulting value with consistent indentation. Parsing errors are shown instead of guessing how malformed data should be repaired.

• Engine: Native JSON.parse and JSON.stringify
• Supported input: valid JSON object, array, string, number, boolean, or null
• Output: indented JSON text, validation error

Input

{"user":{"id":7},"active":true}

Output

A four-line, indented JSON object with user and active fields

Limits, edge cases, and troubleshooting

Use it for API responses, configuration snippets, and test fixtures. A syntax error near the end often comes from a missing quote, bracket, or comma earlier in the document.

• The full document must fit in browser memory.
• Comments, trailing commas, NaN, Infinity, and JavaScript object literals are not valid JSON.

When to use another workflow

Use jq or an IDE for very large files, streaming data, schema validation, or repeatable transformations.

Verification

Reviewed by the Free Online Tools Nest Team on 2026-08-26. The interface, output path, and documented limitations were checked against the current implementation. See our testing methodology for the review process.