Sigmera.

Convert a CSV to Excel (XLSX)

To convert a CSV to Excel, open the converter in Sigmera, drop your .csv file, and download a ready-to-open .xlsx workbook. The conversion happens entirely in your browser — your file is never uploaded to a server, so it’s GDPR-safe by design and works without Excel installed.

Last updated: June 2026

Sigmera converting a CSV file to an Excel .xlsx workbook in the workspace

Use the CSV → Excel converter free in your workspace

Free account, no credit card — every tool, unlimited rows, 3 free downloads a month, nothing uploaded.

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🔒 Everything runs in your browser — your file is never uploaded, and the workspace even works offline once it has loaded.

How to convert CSV to Excel

  1. 1. Open the converter in your free workspace. Your CSV is read into the browser’s memory — never sent over the network.
  2. 2. Drop your .csv file. Sigmera detects the delimiter and encoding automatically, so accents and special characters survive.
  3. 3. Download the .xlsx workbook. The result opens in Excel, Google Sheets, Numbers, or LibreOffice.

Why convert in the browser?

Most online converters upload your file to a server you can’t see. Because Sigmera converts the file locally with the browser’s built-in engine, there is no server to upload to and nothing is stored — which satisfies GDPR data-minimization because zero bytes leave your device.

Need the opposite direction? Use the same workspace to convert XLSX to CSV when an importer refuses .xlsx and wants plain comma-separated text.

Frequently asked questions

Does this tool upload my CSV?
No. The CSV-to-Excel conversion runs entirely inside your web browser using client-side JavaScript. Your file is never uploaded to a server, so it is GDPR-safe by design.
What format does it produce?
A standard .xlsx workbook that opens in Microsoft Excel, Google Sheets, Numbers, and LibreOffice. Your rows and columns are placed on the first sheet exactly as they appear in the CSV.
Will it handle accents and other languages?
Yes. Sigmera auto-detects the CSV's encoding (UTF-8, UTF-16, Windows-1250/1252 and more), so accented and non-Latin characters survive the conversion intact.
Do I need Excel installed?
No. The conversion happens in the browser, so you don't need Excel or any other app installed to produce the .xlsx file.