JSONの理解：フォーマットと検証の初心者ガイド
Quick Answer
JSONはキーと値のペアと配列を使用するテキストベースのデータフォーマットです。文字列、数値、ブール値、null、オブジェクト、配列をサポートします。無料のJSONフォーマッターを使用してJSONデータを整形、検証、最小化 — すべての処理はブラウザ内で行われます。
Introduction
JSON（JavaScript Object Notation）は、人間が読み書きしやすく、機械が解析および生成しやすい軽量のデータ交換フォーマットです。Webサーバーとブラウザ間の通信に使用される最も一般的なデータフォーマットであり、最新のWeb APIではXMLに大きく取って代わりました。
Step by Step
-
Understand JSON syntax
JSON uses curly braces {} for objects, square brackets [] for arrays, and key-value pairs separated by colons. Keys must be strings in double quotes. Values can be strings, numbers, booleans, null, objects, or arrays.
-
Format your JSON
Paste your JSON data into the JSON Formatter tool. It will automatically beautify the JSON with proper indentation and line breaks, making it easy to read.
-
Validate the structure
The formatter checks your JSON for syntax errors. If valid, it displays the formatted output. If invalid, it shows an error message indicating the problem.
-
Copy or use the result
Copy the formatted JSON to your clipboard for use in your code, documentation, or debugging.
Examples
Simple object
Input: {"name":"Alice","age":30}
Output: {
"name": "Alice",
"age": 30
}
Array of objects
Input: [{"id":1},{"id":2}]
Output: [
{ "id": 1 },
{ "id": 2 }
]
Nested structure
Input: {"user":{"name":"Bob","tags":["admin","user"]}}
Output: {
"user": {
"name": "Bob",
"tags": ["admin", "user"]
}
}
Common Problems
- Using single quotes for strings —JSON requires double quotes for strings and keys.
- Trailing commas —JSON does not allow a comma after the last item in an object or array.
- Comments —JSON does not support comments (// or /* */). Use JSONC or JSON5 if you need comments.
- Unquoted keys —all keys must be in double quotes, unlike JavaScript object literals.
Tips
- Use a JSON formatter to catch syntax errors before sending data to an API.
- Minified JSON saves bandwidth —use minification in production, formatting in development.
- JSON does not support undefined, functions, or dates as values —use null or ISO 8601 strings.
- Use JSON.parse() in JavaScript to convert JSON strings to objects, and JSON.stringify() to convert objects to JSON.