How to Convert Excel (XLSX) to JSON with Multiple Sheets

Why JSON from Excel Is Trickier Than It Looks

Excel stores data in a grid, but real workbooks rarely have a single clean table. You might have:

• Multiple sheets representing different entity types (customers, orders, products)
• Column headers with dots or underscores that imply nested structure
• Date, currency, and number formats that need type preservation
• Thousands of rows that exceed what a simple copy-paste can handle

A proper Excel to JSON converter handles these edge cases. The data keeps its meaning through the conversion.

1. Upload and Convert — The Basics

Converting a single-sheet Excel file to JSON takes three steps:

1. Open the Excel to JSON Converter.
2. Click Upload or drop your .xlsx file onto the drop zone.
3. The file is parsed into an editable table. The JSON output appears in the right panel.

The result is an array of objects:

[
  {
    "id": 1,
    "name": "Alice",
    "email": "alice@example.com"
  },
  {
    "id": 2,
    "name": "Bob",
    "email": "bob@example.com"
  }
]

The first row is treated as headers and becomes JSON keys. The remaining rows become values.

2. Working with Multiple Sheets

Workbooks with multiple sheets are common. Here's how the converter handles them:

• Sheet selector: A dropdown list shows all sheets in the workbook. By default, the first sheet is loaded.
• Single-sheet export: When you download JSON, only the currently active sheet is exported — clean and focused.
• Multi-sheet export (coming soon): For full multi-sheet export, each sheet becomes a named key in the JSON structure.

The active sheet indicator shows total rows parsed, so you know exactly how much data you're working with before downloading.

3. Converting to Nested JSON with Unflatten Keys

Many Excel exports use dot-notation column headers like contact.email or address.city. Enable the Unflatten Keys option to transform them into nested JSON automatically:

[
  {
    "name": "Alice",
    "contact": {
      "email": "alice@example.com",
      "phone": "123-456-7890"
    },
    "address": {
      "city": "Beijing"
    }
  }
]

This mirrors real-world API structures. The preview updates instantly, so you can toggle Unflatten Keys on and off to compare the flat vs nested output before exporting.

4. Data Type Preservation and Output Formats

Numbers, dates, and booleans in Excel cells are converted to their proper JSON types:

• Numbers: Numeric cells become JSON numbers (no quotes).
• Booleans: TRUE/FALSE become true/false.
• Dates: Formatted as ISO strings by default.
• Empty cells: Become null in JSON, not empty strings.

Two output formats are available:

• Pretty: Indented and readable — great for debugging and code review.
• Compact: Minified — ideal for API payloads and storage.

Switch between them with the Output Format dropdown. The right panel updates instantly so you can see exactly what you'll get.

Best Practices for Excel to JSON Conversion

• Clean your Excel headers first. Use clear, unique column names without special characters. For nested output, use dot notation like user.email instead of user_email.
• Pick the right sheet. If your workbook has summary sheets or chart sheets, skip them — only convert the data sheets.
• Preview before downloading. The table view shows exactly what will be converted. Check for unexpected nulls or merged cells.
• Remove formatting rows. Delete any title rows, subtotals, or summary rows from the table before exporting. Use the editable table in the converter to clean them up.
• For simple CSV data, bypass Excel entirely. If your source is already a CSV, use the CSV to JSON converter for a lighter workflow.

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