CSV to Excel

What goes wrong when Excel opens a CSV

• Garbled characters — CSVs are saved in different encodings. Excel often misreads UTF-8 files without a BOM, so “Müller” turns into “Müller”.
• Disappearing zeros — ZIP codes like 02134, phone numbers starting with 0 and employee IDs like 00123 lose their leading zeros.
• Mangled long numbers — card or order numbers longer than 15 digits become 1.23E+15 and their last digits turn into zeros.

This tool reads the raw bytes to detect the encoding and delimiter, then keeps those values as text while building a real Excel file. Ordinary numbers become numbers you can calculate with, and values like 2026-11-09 become dates.

How to use it

1. Drop CSV files to see the detected encoding, delimiter and the first five rows. If characters look wrong, pick the encoding yourself.
2. Click “Download Excel” for an .xlsx with a bold header row, filters and frozen panes.
3. Several files can be downloaded as separate .xlsx files (ZIP) or as sheets in one workbook.

Files are never uploaded. Even files of tens of MB work in a desktop browser.