JSON Formatter

JSONデータの整形、検証、圧縮。
入力
出力

Beautify & Minify

Format JSON with customizable indentation (2 spaces, 4 spaces, or tabs), or compress it into a single minified line.

Validate

Instantly detect syntax errors with clear, actionable error messages showing exactly where the problem is.

Syntax Highlighting

Color-coded JSON output for easy reading — keys, values, strings, and numbers are visually distinct.

Private & Client-side

All processing happens in your browser. Your JSON data is never uploaded to any server.

JSON Formatterについて

JSON (JavaScript Object Notation) is the most widely used data interchange format in modern web development. Whether you're working with REST APIs, configuration files, or debugging application data, having a reliable JSON formatter saves significant time. Our JSON Formatter parses your raw JSON string, identifies any syntax errors immediately, and outputs a neatly indented, human-readable version — or a compact minified version for production use. It supports all valid JSON types including objects, arrays, strings, numbers, booleans, and null values.

JSON Formatterの使い方

  1. Paste your raw or minified JSON into the left input panel, or click "Load Sample" to try an example.
  2. Choose your preferred indentation level — 2 spaces, 4 spaces, or tabs — using the Indent selector.
  3. Click "Format" to beautify the JSON with proper indentation and line breaks.
  4. Click "Minify" to compress the JSON into a single line for smaller file sizes.
  5. If there are any syntax errors, a red error message will appear describing exactly what is wrong.
  6. Click "Copy" to copy the formatted or minified output to your clipboard.

よくある質問

Is my JSON data sent to a server?

No. The JSON Formatter runs entirely in your browser using JavaScript. Your data is never uploaded, stored, or transmitted to any server. This makes it safe to format sensitive API responses or configuration files.

What is the difference between formatting and minifying JSON?

Formatting (beautifying) adds indentation and line breaks to make the JSON structure easy for humans to read and understand. Minifying removes all whitespace to produce the smallest possible file size, which is preferred for network transmission and production environments.

Why is my JSON showing an error?

Common JSON errors include trailing commas (e.g., the last item in an array or object has a comma), unquoted keys (JSON requires all keys to be double-quoted strings), single quotes instead of double quotes, or missing colons between keys and values.

Can I format JSON with comments?

Standard JSON does not support comments. If your JSON contains comments (often called JSON5 or JSONC format), you will need to remove them before formatting. Some editors like VS Code support JSONC files natively.

What indentation style should I use?

2 spaces is the most common style used by tools like Prettier and is recommended for most projects. 4 spaces is common in Python and some older JavaScript style guides. Tab indentation is preferred in some teams because it allows each developer to choose their preferred tab width in their editor.

JSON Formatterの完全ガイド：無料オンラインツール

ブラウザ完結で安全・高速なJSON Formatter。開発者やクリエイターの作業を効率化

JSONデータの整形、検証、圧縮。を瞬時に実現する無料ツールです。面倒なソフトのインストールは不要で、安全にブラウザ上で処理できます。

JSON Formatterが選ばれる理由

  • 高速処理: ミリ秒単位で即時実行。
  • プライバシー保護: データは端末外に送信されません。
  • 完全無料: 登録不要で制限なく利用可能。

簡単な3つの利用手順

  1. JSON Formatterのページを開きます。
  2. データを入力または貼り付けます。
  3. 結果を確認してコピーまたは保存します。

機能比較

項目 Metoolzy JSON Formatter 他社オンラインツール 専用ソフト
料金 完全無料 制限あり 有料ライセンス
セキュリティ 完全ローカル処理 サーバー送信あり ローカル処理

主な活用シーン

  • エンジニアの開発・デバッグ効率化
  • Web制作者の日常作業
  • データ変換・最適化

よくある質問 (FAQ)

入力したデータは保存されますか？

いいえ、すべてブラウザ内で処理され保存されません。