JSON Formatter & Validator

How to Use This Tool

1. Paste your raw JSON string into the input field. It can be minified, partially formatted, or copied straight from a terminal or API client.
2. Choose an action: click Format to beautify with indentation, or Minify to compress into a single line.
3. If the JSON is invalid, the tool highlights the exact error with line and character details. Fix the issue in the input and try again.
4. Copy the formatted or minified output to your clipboard with the copy button and paste it into your editor, config file, or API request.

Examples

{"name":"Alice","age":30,"roles":["admin","editor"],"active":true}

{
  "name": "Alice",
  "age": 30,
  "roles": [
    "admin",
    "editor"
  ],
  "active": true
}

{"name": "Alice", "age": 30,}

Unexpected token } at position 28 — trailing comma after the last property is not allowed in JSON.

{
  "status": "ok",
  "count": 42
}

{"status":"ok","count":42}

What This Tool Is Useful For

• API debugging: Paste a compressed API response to see its structure clearly and spot unexpected values or missing fields.
• Config file editing: Format JSON configuration files (package.json, tsconfig.json, etc.) before making manual edits to avoid introducing syntax errors.
• Data validation: Quickly check whether a JSON string is valid before passing it to a parser, database import, or deployment script.
• Payload optimization: Minify JSON before embedding it in URL parameters, storing it in a database field, or sending it in a webhook body.
• Code review preparation: Beautify JSON fixtures and sample data so reviewers can read the structure without scrolling through a single long line.

Frequently Asked Questions

What makes JSON invalid?

The most common causes are trailing commas after the last item in an array or object, single quotes instead of double quotes around keys or string values, unquoted keys, missing commas between items, and unescaped special characters inside strings such as literal newlines or tabs.

What is the difference between formatting and minifying JSON?

Formatting (beautifying) adds indentation and line breaks so you can read the structure at a glance. Minifying does the opposite — it strips all optional whitespace to produce the smallest possible string. Use formatting when you need to inspect or edit the data; use minifying when you need to reduce payload size for network transfer or storage.

Is there a maximum size for the JSON I can paste?

There is no hard limit enforced by the tool. Because all processing runs in your browser, performance depends on your device. Most modern computers handle files up to several megabytes without any noticeable delay.

Does formatting change the data in any way?

No. Formatting only adds or removes whitespace characters. The actual data — keys, values, arrays, and nesting — stays identical. You can verify this by minifying the formatted output and comparing it to the original.

Can I format JSON with comments?

Standard JSON does not support comments. If your input contains JavaScript-style comments (// or /* */), the validator will flag it as invalid. You would need to remove comments before formatting. Some config formats like JSONC allow comments, but they are not valid JSON per the specification.

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