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JSON to CSV for Excel

Convert JSON arrays into CSV files ready for Excel. Handles nested objects, arrays, and Unicode with BOM.

JSON Input

CSV Output

What Is JSON to CSV for Excel?

Converting JSON to CSV is a common task when you need to analyze API data, database exports, or configuration files in Excel. This tool converts JSON arrays into properly formatted CSV files that open correctly in Excel — with a BOM (Byte Order Mark) for correct UTF-8 encoding, proper quoting of values containing commas or quotes, and flattening of nested objects.

Why CSV for Excel Needs a BOM

Excel has a long-standing issue with UTF-8 encoded CSV files. Without a BOM (\uFEFF) at the start of the file, Excel assumes the file is encoded in the system's default ANSI codepage, which breaks special characters, emoji, and non-Latin text. This tool automatically prepends the BOM so your data displays correctly in Excel, Google Sheets, and LibreOffice Calc.

How Nested Data Is Handled

JSON data often contains nested objects and arrays. This converter flattens nested objects using underscore notation. For example, a JSON object like {"user": {"name": "Alice", "age": 30}} becomes two CSV columns: user_name and user_age. Nested arrays are converted to JSON strings within the cell, preserving the full data.

Use Cases

API Data Export — Convert REST API JSON responses into spreadsheets for reporting.
Database Migration — Export database records as JSON and convert to CSV for import into Excel.
Data Analysis — Transform JSON datasets into tabular format for pivot tables and charts.
Client Reports — Generate CSV files that non-technical stakeholders can open in Excel.

How to Use

Paste a JSON array into the input field and click Convert to CSV. The output shows the CSV data that's ready for Excel. Use Copy CSV to copy to clipboard, or Download .csv to save a file with the BOM included. The row count is displayed above the output so you know how many records were converted.

How to Do This in Code

function jsonToCsv(json, flatten = true) {
  const items = Array.isArray(json) ? json : [json];
  if (!items.length) return '';
  const keys = [...new Set(items.flatMap(obj => flattenKeys(obj)))];
  const csv = [keys.join(','), ...items.map(item =>
    keys.map(k => {
      const val = flatten ? getFlattened(item, k) : item[k];
      const str = val == null ? '' : String(val);
      return str.includes(',') || str.includes('"') || str.includes('\n')
        ? '"' + str.replace(/"/g, '""') + '"'
        : str;
    }).join(',')
  )].join('\n');
  return '\uFEFF' + csv; // BOM for Excel
}

import json, csv, io

def json_to_csv(json_str):
    data = json.loads(json_str)
    if not data:
        return ''
    output = io.StringIO()
    # Flatten nested objects
    def flatten(obj, prefix=''):
        items = {}
        for k, v in obj.items():
            key = f'{prefix}{k}'
            if isinstance(v, dict):
                items.update(flatten(v, key + '_'))
            else:
                items[key] = v
        return items
    flat = [flatten(row) for row in data]
    writer = csv.DictWriter(output, fieldnames=flat[0].keys())
    writer.writeheader()
    writer.writerows(flat)
    return output.getvalue()

# Convert JSON to CSV with jq
cat data.json | jq -r '(.[0] | keys_unsorted) as $keys | $keys, (.[] | [.[$keys[]]] | @csv)' > output.csv

# Add BOM for Excel compatibility
printf '\uFEFF' | cat - output.csv > excel_ready.csv

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JSON to CSV for Excel FAQ

Why won't my CSV open correctly in Excel?

Excel often misreads UTF-8 CSV files without a BOM (Byte Order Mark). This tool adds a BOM (\uFEFF) automatically, so your CSV opens with correct encoding in Excel, including special characters and emoji.

How are nested objects handled?

Nested objects are flattened with underscore notation. For example, {"user": {"name": "John"}} becomes a column named user_name. Nested arrays are converted to JSON strings within the cell.

Can I convert large JSON files?

Yes, the conversion runs entirely in your browser. However, very large files may be slow. For optimal performance, keep files under 10MB. There is no server upload — everything stays on your device.