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Runs in your browserConvert CSV to Excel
Opening a CSV in Excel and saving it as .xlsx works, until Excel decides your product codes are numbers and strips the leading zeros. This writes a real workbook directly, keeps anything that would be damaged by conversion as text, and can combine several CSVs into one workbook with a sheet for each.
How to use it
- Choose one or more CSV files. Each becomes its own sheet, named after the file.
- Decide whether numbers should become real numbers rather than text.
- Click Convert and download the .xlsx.
Questions
Is my file uploaded anywhere?
No. This page contains the whole tool — the JavaScript that does the work runs inside your browser tab, on your own machine. There is no server to upload to. You can confirm it yourself: open your browser's developer tools, switch to the Network tab, and run the tool. You will not see your file go anywhere. You can also disconnect from the internet after the page loads and it will still work.
Will it destroy my leading zeros?
No. A value is only converted to a number when it round-trips exactly, so 01234 and +61400000000 stay as text while 1234 becomes a number. This is the single most common way CSV-to-Excel conversion quietly corrupts data, and it's the reason this tool exists.
Can I put several CSVs in one workbook?
Yes — add them all and each becomes a sheet, named after its file. Duplicate names get a number appended, because Excel refuses two sheets with the same name.
Why is my sheet name shortened?
Excel caps sheet names at 31 characters and forbids : \ / ? * [ and ]. Anything longer is truncated and those characters are replaced, otherwise the file wouldn't open.