JSON Formatter & Validator

What is the JSON Formatter?

The JSON Formatter takes minified, machine-generated, or hand-edited JSON and rewrites it with consistent indentation and line breaks so you can actually read it. It also parses the document as it formats, so a syntax error is reported with the line and column where the parser gave up rather than a generic failure message.

JSON (JavaScript Object Notation) is the default data format for web APIs, configuration files, package manifests, and log pipelines. It is easy for machines to emit but painful for humans to read once whitespace is stripped, a single-line API response of a few kilobytes is effectively opaque.

Formatting solves the readability half of that problem, and validation solves the correctness half. This tool does both in the same pass: if the text parses, you get a beautified document; if it does not, you get the exact position of the first structural error.

How to use the JSON Formatter

1. Paste your JSON. Drop the raw text into the input editor on the left. There is no size limit imposed by the tool beyond what your browser can hold in memory.
2. Choose an indent width. Two spaces is the common default for JavaScript and TypeScript projects; four is conventional in Python and Java codebases. Pick whichever matches the repository you are pasting into.
3. Click Format JSON. The formatted result appears in the right editor with syntax highlighting applied.
4. Or click Minify JSON. This performs the inverse operation, stripping every non-significant byte of whitespace to produce the smallest valid representation of the same data.
5. Download or copy the result. Use Download to save the output as a .json file, or select and copy it straight out of the editor.

Worked examples

{"data":[{"id":1,"name":"Ada Lovelace","role":"admin"},{"id":2,"name":"Alan Turing","role":"user"}],"page":1,"total":2}

{
  "data": [
    {
      "id": 1,
      "name": "Ada Lovelace",
      "role": "admin"
    },
    {
      "id": 2,
      "name": "Alan Turing",
      "role": "user"
    }
  ],
  "page": 1,
  "total": 2
}

{
  "host": "localhost",
  "port": 5432,
}

Invalid JSON: Unexpected token } in JSON at position 44
Error at line 4, column 1

Common use cases

• Debugging API integrations. When a request fails, formatting the response body is usually the fastest way to see whether the server returned the payload you expected or an error envelope in a different shape.
• Reviewing configuration files. Files such as package.json, tsconfig.json, and composer.json are easier to diff and reason about when indentation is consistent across a team.
• Cleaning up log output. Structured loggers emit one JSON object per line. Pulling a single line out and formatting it makes the fields legible when you are chasing a specific event.
• Preparing fixtures for tests. Readable fixture files make test failures easier to interpret, since the diff points at a named field rather than a character offset.

Features and limitations

• Formats and minifies in the same interface, so you can round-trip between the two representations.
• Reports the line and column of the first syntax error instead of failing silently.
• Tolerates unquoted object keys on input as a convenience, rewriting them as quoted keys in the output.
• Preserves the order of object members as they appear in the source document.
• Numbers are handled by the browser's own JSON parser, which means integers beyond 2^53 lose precision, a limitation of the JSON number type itself, not of this tool. Use strings for large identifiers.
• Comments are not supported, because they are not part of the JSON specification. Strip them before pasting, or use a JSONC-aware editor.

Frequently asked questions