Which Excel formats are supported?

Convertee supports .xlsx (Office Open XML) and .xls (legacy BIFF format). The .xlsx format is recommended for best compatibility.

Does it read multiple sheets?

Currently, Convertee reads the first sheet. Multi-sheet support is planned for a future update.

How are dates in Excel handled?

Excel stores dates as serial numbers. Convertee converts them to ISO 8601 strings (e.g., '2026-04-14') in the JSON output so they are human-readable and easy to parse programmatically.

Is my Excel file uploaded to a server?

No. The file is read and parsed entirely in your browser using the SheetJS library. No data is transmitted over the network.

How to Convert Excel to JSON: Complete Guide

Last updated: 2026-04-14

Excel is the default format for business data. JSON is what your code expects. Bridging the two is a daily task for developers who work with product teams, analysts, or clients who live in spreadsheets. Convertee parses .xlsx files locally using the SheetJS library and outputs clean JSON — no file upload, no cloud processing.

Step-by-Step: Convert Excel to JSON with Convertee

Open Convertee, select Excel as source and JSON as target.
Drag-and-drop your .xlsx (or .xls) file onto the input panel. Convertee reads the first sheet by default.
Adjust JSON options: indent level and root structure (array of objects or array of arrays).
Click Convert (Cmd+Enter).
Copy or download the JSON.

The file is parsed entirely in your browser using SheetJS. No data is sent to any server.

Understanding the Formats

Excel (.xlsx)

The Office Open XML Spreadsheet format (.xlsx) is specified by ECMA-376. Under the hood, an .xlsx file is a ZIP archive containing XML files that describe sheets, styles, shared strings, and formulas. SheetJS handles the unzipping and XML parsing, exposing rows and cells as JavaScript objects.

JSON

JSON (RFC 8259) maps naturally to spreadsheet data: each row becomes an object, each column header becomes a key. Numeric cells stay as numbers; dates are converted to ISO 8601 strings by default.

Before / After Example

Suppose your Excel file has this data (first sheet):

product	quantity	price
Laptop	5	1299.00
Monitor	12	399.00

Output JSON:

[
  { "product": "Laptop", "quantity": 5, "price": 1299 },
  { "product": "Monitor", "quantity": 12, "price": 399 }
]

Common Use Cases

Importing product catalogs. E-commerce teams maintain SKU lists in Excel. Developers need JSON for the product API or CMS import.
Test data generation. QA engineers maintain test cases in Excel and convert them to JSON fixtures for automated test suites.
Static site content. Blog posts, FAQ entries, or translation tables managed in Excel can be converted to JSON for static site generators (Next.js, Astro, etc.).
Data science preprocessing. Before loading data into a Jupyter notebook via pandas.read_json(), converting the Excel source to JSON can be simpler than dealing with openpyxl version mismatches.

Options and Configuration

Option	Default	What It Does
JSON indent	2 spaces	Sets the indentation of the output. Choose 2 or 4 spaces, tabs, or minified.
Root structure	Array of objects	`records` uses header row as keys. `arrays` outputs raw row arrays without keys.
Header row	On	Treats the first row of the sheet as column headers. Disable if your data starts on row 1 without headers.

Frequently Asked Questions

Which Excel formats are supported?: Convertee supports .xlsx (Office Open XML) and .xls (legacy BIFF format). The .xlsx format is recommended for best compatibility.
Does it read multiple sheets?: Currently, Convertee reads the first sheet. Multi-sheet support is planned for a future update.
How are dates in Excel handled?: Excel stores dates as serial numbers. Convertee converts them to ISO 8601 strings (e.g., '2026-04-14') in the JSON output so they are human-readable and easy to parse programmatically.
Is my Excel file uploaded to a server?: No. The file is read and parsed entirely in your browser using the SheetJS library. No data is transmitted over the network.