How the conversion works
The first row is the header; each later row becomes an object whose keys are the header names. Quoted fields follow RFC 4180, so commas and line breaks inside "double quotes" stay in the cell and "" becomes a literal quote. The delimiter is detected from the header line — comma, semicolon (common in European Excel exports), tab or pipe — or you can set it yourself.
With "Detect numbers & booleans" on, 98.5 becomes a number, true a boolean and empty cells null; values with leading zeros such as 007 or 02134 stay strings so nothing is lost. Turn it off to keep every value as a string, exactly as CSV stores it. Rows with more or fewer fields than the header are reported.
Frequently asked questions
Does the first row have to be a header?
Yes, the first row supplies the keys. Blank header cells are named column1, column2 and so on.
How do I convert a semicolon-separated file?
Leave the delimiter on Auto — it detects semicolons, tabs and pipes from the first line — or pick ; explicitly.
Why are some numbers kept as strings?
Values with leading zeros (zip codes, IDs) and very long digit strings stay as strings, because converting them to numbers would drop the zeros or lose precision beyond 15 digits.
Can I convert Excel files directly?
Not .xlsx files. In Excel or Google Sheets use File → Download/Save as → CSV, then paste or open the CSV here.
Is my data uploaded?
No. Parsing happens in your browser.