Free Developer Tool — 100% Client-Side

JSON to CSV for Excel

Name: JSON to CSV for Excel - WebUtil
Author: WebUtil

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.

Converting hierarchical JSON data into flat CSV (Comma-Separated Values) format is one of the most common data wrangling tasks in business analytics, data science, and web development. While JSON is the native format for web APIs, NoSQL databases, and application logs, business analysts and spreadsheet tools like Microsoft Excel, Google Sheets, and Tableau require flat tabular structures with rows and columns. Flattening nested JSON into CSV involves complex edge cases: nested object properties must be unrolled into column headers (e.g. `user.address.city` becomes `user_address_city`), nested arrays must be serialized without breaking CSV delimiters, and values containing commas, quotes, or newlines must be properly escaped according to RFC 4180. A major source of frustration when opening CSV files in Microsoft Excel is character encoding: Excel defaults to local legacy encodings unless a UTF-8 Byte Order Mark (BOM: `\uFEFF`) is prepended to the file. Without BOM, international characters, accented names, and currency symbols display as corrupted text (mojibake). WebUtil's JSON to CSV Converter flattens nested JSON, formats values per RFC 4180, embeds an Excel-compatible UTF-8 BOM, and renders an interactive table preview with instant CSV download—100% in-browser.

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

Popular Developer Tools

JSON Formatter

Format, validate, and beautify JSON data

Base64 Encoder

Encode and decode Base64 instantly

JWT Decoder

Decode and inspect JWT tokens

Regex Tester

Test regular expressions in real-time

Hash Generator

Generate MD5, SHA-1, SHA-256 hashes

Deploy Your Next Project Fast

Get $200 free credit on DigitalOcean to deploy your apps with blazing-fast infrastructure.

Try DigitalOcean

Related Tools

JSON Formatter

Format, validate, and beautify your JSON data with syntax highlighting and error detection.

YAML to JSON Converter

Convert YAML data to JSON format and vice versa with live preview.

SQL Formatter

Format and beautify SQL queries for better readability and maintainability.

Related Guides & Tutorials

Formatters 8 min read

JSON to CSV Conversion: The Complete Developer's Guide

Learn how to convert JSON to CSV in JavaScript, Python, and online tools. Handle nested objects, arrays, and large datasets efficiently.

JSON to CSV for Excel FAQ

Why does my CSV export look scrambled in Microsoft Excel, and how does BOM fix it?

Excel often defaults to legacy system encodings instead of UTF-8. WebUtil adds a UTF-8 Byte Order Mark (\uFEFF) to the start of the CSV file, forcing Excel to read accents, symbols, and international characters correctly.

How does this tool flatten deeply nested JSON objects and arrays?

Nested object keys are flattened using underscore notation (e.g. user: { name: 'Alex' } becomes column user_name). Arrays are converted into compact JSON strings within the cell.

What is RFC 4180 and how are quotes and commas escaped in CSV?

RFC 4180 is the official CSV specification. Any cell containing commas, newlines, or quotation marks is enclosed in double quotes, and internal quotes are escaped by doubling them ("").

Can I convert large JSON API payloads without browser lag?

Yes. WebUtil's flattening and serialization engine processes thousands of records in milliseconds using optimized array iterators inside your browser.

Is any of my financial or customer JSON data uploaded to a server?

No. All parsing, flattening, table rendering, and file generation runs client-side in your browser. Nothing is uploaded, logged, or tracked.