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ToT ToolsOfTools

JSON Formatter & Validator

Format and validate raw JSON instantly in your browser. Beautify minified payloads, fix syntax bugs, sort object keys, and compress for production APIs.

Paste your JSON here to format, minify, or validate it

Formatted JSON
{ "name": "ToolsOfTools", "version": "1.0", "features": [ "format", "minify", "validate" ] }
Validation Status
Valid ✓
Formatted Length (chars)
112
Minified Length (chars)
81
Minified JSON
{"name":"ToolsOfTools","version":"1.0","features":["format","minify","validate"]}

使い方

計算式

JSON.stringify(JSON.parse(input), null, indentLevel)

計算例

Minified payload '{"a":1,"b":[true,false]}' beautified with 2 spaces indents cleanly into a readable multi-line structure with syntax verification.

Why Use an In-Browser JSON Formatter?

JSON (JavaScript Object Notation) is the dominant standard for REST APIs, GraphQL payloads, configuration files (tsconfig.json, package.json), and NoSQL document databases. Raw API responses are often minified into single, unreadable strings of thousands of characters.

Essential Rules of Valid JSON (RFC 8259)

When debugging parse errors, verify the following strict rules:

  1. Double Quotes Only: All string literals and property keys must use double quotes "". Single quotes '' are invalid syntax.
  2. No Trailing Commas: Commas must only separate elements. [1, 2, 3,] is illegal in JSON.
  3. No Comments: Unlike JavaScript, pure JSON does not allow // single line or /* multi line */ comments.
  4. Valid Values: Valid JSON data types are: string, number, boolean, null, object, and array. Functions, undefined, and NaN cannot be represented.

Indentation Comparison

  • 2 Spaces: Standard for modern web development, TypeScript configs, and cloud configs.
  • 4 Spaces: Traditional standard for Python, Java, and enterprise systems.
  • Minified (0 Spaces): Recommended for production HTTP responses to reduce bandwidth and latency.

よくある質問

What causes 'Unexpected token' errors in JSON?

Common JSON syntax errors include: trailing commas after the last item in arrays or objects, unquoted object keys (JSON requires double quotes around keys), using single quotes instead of double quotes, and comments (which are not valid in standard RFC 8259 JSON).

Is JSON formatting safe for sensitive credentials and API keys?

Yes. Our tool is 100% client-side. The JSON parser runs entirely in your browser's V8 engine without ever transmitting payloads over the internet.

What is the difference between JSON beautification and minification?

Beautifying adds newlines and indentation spaces to make complex nested data readable for human inspection. Minification strips all whitespace, newlines, and comments to reduce payload size over the network.

Can I sort object keys alphabetically?

Yes, our tool supports key sorting, which is especially useful when performing git diff comparisons between two configuration or localization files.

参照元:
最終更新日: 2026年3月19日

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