Quoting, and why it matters
Any value containing the delimiter, a quote mark or a line break is wrapped in quotes and its own quotes doubled, which is what RFC 4180 asks for and what every spreadsheet and database import expects. Get this wrong and a single address field with a comma in it silently shifts every column after it.
The UTF-8 BOM option
Excel on Windows reads a plain UTF-8 CSV as the local codepage, so accented letters and Chinese or Japanese text arrive as mojibake. Ticking Excel-friendly puts a byte-order mark at the front, which tells Excel to read it as UTF-8. Leave it off for anything that is going into a script or a database — many parsers treat the mark as part of the first column name.
Frequently asked questions
Is my spreadsheet uploaded anywhere?
No. Everything happens in your browser. The file never reaches a server, so there is nothing to delete afterwards.
Can I get every sheet at once?
Yes. When a workbook has more than one sheet, an "All sheets" button appears and gives you a zip with one CSV per sheet, named after the tabs.
My numbers look different from Excel.
CSV has no formatting, so a cell displayed as £1,234.50 is written as 1234.5. The value is the same; only the presentation Excel applied is gone.
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