JSON Formatter & Validator

Format, validate, and beautify JSON with syntax highlighting and error detection.

  • Developer & Code
  • Runs in your browser
  • Free, no signup

How to use

How to Use JSON Formatter & Validator

  1. 1

    Paste your JSON

    Enter the JSON string you want to format and validate.

  2. 2

    Format the output

    Click format to pretty-print with proper indentation.

  3. 3

    Copy formatted JSON

    Click copy to grab the cleanly formatted JSON output.

The guide

Tested tool guide Developer and data tools Checked July 30, 2026

What JSON Formatter & Validator does, with a checked example

Use this formatter when a JSON document is difficult to read or a parser rejects it. The tool runs JSON.parse to validate the input, then JSON.stringify to produce either indented or compact output. It does not repair invalid JSON silently, so a syntax error remains visible instead of being guessed away.

Worked example

A concrete input and expected output from the current implementation.

Input

{"name":"b2KIT","private":true,"tools":2769}

Expected output

{
  "name": "b2KIT",
  "private": true,
  "tools": 2769
}

With two-space indentation selected, the three properties are placed on separate lines. The strings, Boolean value, and number keep their original JSON types.

How the result is produced

1

Parsing comes before formatting

The browser first parses the entire document as JSON. Missing quotes, trailing commas, comments, and unescaped control characters are rejected because they are outside the JSON grammar.

2

Formatting does not change the data model

Pretty printing changes whitespace only. Minification removes optional whitespace, but property names, array order, values, and nesting remain the same after a successful parse.

Good uses

  • Inspect an API response before debugging application code.
  • Normalize configuration snippets for a code review.
  • Minify a validated payload before copying it into a request.

Limits and checks

  • JSON strings and property names require double quotes.
  • Very large documents may be easier to inspect in a streaming or command-line parser.
  • Formatting cannot confirm that fields have the right business meaning or schema.

Common questions

Will formatting reorder object properties?

No. This implementation serializes the parsed object in its existing property order. Consumers should still avoid treating JSON object order as a data contract.

Does validation send the document to a server?

No. Parsing and serialization happen in the browser. Avoid pasting secrets into any shared or untrusted device even when processing is local.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.