CSV to Excel
Turn CSV into a real .xlsx with numbers as numbers — leading zeros protected.
About this tool
Paste CSV or choose a file, check the preview, download a genuine .xlsx that opens in Excel, Google Sheets, Numbers and LibreOffice. Parsing and writing happen on your device.
Why not just open the CSV in Excel
Because Excel “helps”. Open a CSV directly and it strips leading zeros from postcodes, ZIP codes, product IDs and phone numbers (007 becomes 7), turns long digit strings into scientific notation (a 16-digit card or tracking number becomes 1.23E+15 and loses its last digits for good), reinterprets 3/4 as a date, and guesses the delimiter wrong for semicolon files. This tool parses the CSV properly — delimiter sniffed from the data, quoted fields with embedded commas and line breaks handled to the standard — and writes a real workbook where numbers are numbers (so you can sum them) and text is text. Tick “keep everything as text” for files full of identifiers and the zeros survive. Honest scope: one sheet, values only, no formatting; that is what a CSV contains. The result is a standard Office Open XML file, not a CSV renamed. Preview or clean the data first in the CSV viewer; convert from JSON with JSON to CSV; the reverse trip is Excel to CSV.
Frequently asked questions
Will leading zeros be kept?
Tick 'keep everything as text' and yes — every cell is written as text. Otherwise numeric-looking values become numbers, which is what you want for sums but not for IDs.
Does it handle semicolons and tabs?
Yes — the delimiter is detected from the first line: comma, semicolon, tab or pipe.
Is it a real Excel file?
Yes — a standard .xlsx (Office Open XML) that Excel 2007+, Google Sheets, Numbers and LibreOffice open without warnings.
Is my data uploaded?
No — parsing and the workbook are produced in your browser.