CSV · JSON · Excel converter
Convert spreadsheet files between formats without uploading your data.
🔒 Your data never leaves your devicePreview (first 20 rows)
Why characters get mangled in CSV
A CSV file carries no information about its own encoding, so every program has to guess. Excel in
particular assumes your system's legacy code page unless the file begins with a short marker called a
BOM — which is why names with accents, umlauts, Cyrillic or CJK characters so often arrive as
é or 샘. This converter detects the incoming encoding, and always writes a
BOM when exporting CSV, so the file opens correctly in Excel without any manual import step.
Frequently asked questions
Is my data uploaded?
No. The conversion runs in your browser, which matters when the spreadsheet contains customer records or financial data.
What shape does the JSON need to be?
An array of objects, for example [{"name":"Ada","age":36}]. Deeply nested values cannot become table cells and are stored as text.
My CSV opens with every row squeezed into one column.
The file is not comma-separated. CSV files exported in Europe and Latin America are usually separated by semicolons (;). Pick semicolon or tab under "Delimiter" and the preview is rebuilt straight away.
Can I save a semicolon-separated CSV?
Yes. Whatever you pick under "Delimiter" is also used when saving. Choose semicolon if the file is going to be opened in Excel with a European locale.
My Excel file has several sheets.
A sheet selector appears. Pick the one you want and convert it; one sheet is converted at a time.
Are formulas and formatting kept?
Only values are converted. Formulas become their calculated result, and cell colours and fonts are not preserved.
Is there a size limit?
No imposed limit, though files with hundreds of thousands of rows may make the browser sluggish.