CSVからJSON
トレンド 🔥CSVデータをJSON形式に即座に変換します。
CSVからJSON の使い方
- 1CSVデータを貼り付ける（最初の行=ヘッダー）
- 2「JSONに変換」をクリックする
- 3JSON出力をコピーまたはダウンロードする
CSVからJSON について
CSV→JSONコンバーターはカンマ区切り値（CSV）データを受け取り、JSONオブジェクトの配列に変換します。CSVの最初の行はプロパティ名として扱われます。すべての変換はブラウザ内で完全に実行されます。
CSVからJSONの主な機能
- Convert CSV data to a JSON array of objects instantly
- First row of CSV is automatically used as property keys
- Handles quoted fields containing commas, quotes, or newlines
- Supports both Windows (CRLF) and Unix (LF) line endings
- Outputs formatted, pretty-printed JSON for readability
- Works entirely in-browser — no file upload or server required
- Copy or download the JSON output with one click
- Handles large CSV files smoothly in the browser
対応フォーマット
入力フォーマット
出力フォーマット
最初の行はヘッダー行である必要があります。すべての値は文字列として出力されます。
使用例
Convert a product list CSV to JSON
Transform an exported spreadsheet into a JSON array ready for an API or database import.
入力
name,price,stock Widget A,9.99,120 Widget B,24.50,45
出力
[{"name":"Widget A","price":"9.99","stock":"120"},{"name":"Widget B","price":"24.50","stock":"45"}]Convert CSV with quoted fields containing commas
Handle CSV fields that contain commas by wrapping them in double quotes.
入力
city,country "New York, NY",USA "London, UK",UK
出力
[{"city":"New York, NY","country":"USA"},{"city":"London, UK","country":"UK"}]主な使用ケース
- Transforming database export CSV files into JSON for API ingestion
- Converting Excel/Google Sheets exports to JSON for JavaScript applications
- Preparing CSV data from legacy systems for modern REST APIs
- Prototyping with real data by quickly converting spreadsheet exports
- Converting survey result exports from CSV to JSON for analysis tools
- Migrating data between systems that use different serialization formats
トラブルシューティング
Extra empty objects appear at the end of the JSON array
解決策
This is caused by trailing newlines in the CSV. Remove any blank lines at the end of your CSV before converting.
Fields with commas are split incorrectly
解決策
Fields containing commas must be wrapped in double quotes in the CSV (e.g., "New York, NY"). Ensure your source data is properly quoted per the CSV standard.
Numbers appear as strings in the JSON output
解決策
The converter outputs all values as strings for safety. If your application requires numeric types, parse the strings in your code using parseInt() or parseFloat() after importing.
よくある質問
What delimiter is used?
The tool expects comma-separated values (CSV). Tab-separated (TSV) and semicolon-separated files are not currently supported. If your file uses a different delimiter, replace it with commas before converting.
How are numbers and booleans handled?
All values are output as JSON strings. Type conversion is not applied automatically — if you need numeric or boolean types, parse the output in your application code.
What happens if a field contains a comma?
Fields containing commas must be enclosed in double quotes in the CSV (e.g., "value with, comma"). The parser correctly handles RFC 4180-compliant quoted fields.
What if my CSV has no header row?
The first row is always treated as the header row. If your CSV has no headers, manually add a header row with column names before pasting it into the tool.
Can I convert a CSV file directly?
Yes, you can paste CSV content directly or, if a file upload option is available, load the file from your device. No data is sent to a server — the conversion runs entirely in your browser.
What is the maximum CSV size I can convert?
There is no server-imposed limit. The practical limit depends on your browser's memory. CSVs with tens of thousands of rows typically convert in under a second on modern hardware.
How do I handle CSV with special characters?
The tool handles UTF-8 encoded CSV, including accented characters, emoji, and other Unicode characters. Ensure your source CSV is saved as UTF-8 to avoid encoding issues.
Is my data sent to a server?
No. All processing is done entirely in your browser. Your CSV data never leaves your device and is not stored or logged anywhere.