Free web tool
Convert a selected Excel sheet to CSV, or UTF-8 / Shift_JIS CSV to Excel, with preview, delimiter and BOM options, and leading-zero preservation.
Move between Excel and CSV without pretending the two formats preserve the same things. Excel→CSV exports the displayed values from one worksheet; CSV→Excel writes CSV values into an .xlsx workbook as text so identifiers such as leading-zero codes are less likely to be reinterpreted.
Excel can hold multiple sheets, formulas, formatting, and cell types. CSV is essentially rows and columns of text. This tool exports the displayed values from the selected worksheet; it does not carry the workbook appearance into CSV.
Identifiers such as 00123 are written as strings so leading zeros are preserved. The trade-off is that the converter does not guess which columns should become numeric/date cells for calculation.
A BOM can make UTF-8 CSV easier for some Windows Excel workflows to recognize, while web systems may explicitly require UTF-8 without BOM. The destination specification wins when one exists.
Blank or effectively empty CSV/TSV input is rejected instead of producing an empty workbook that looks successful. CSV→Excel is also limited to 200,000 rows.
Export one catalog worksheet to CSV for an ecommerce upload, or turn a Shift_JIS CSV into .xlsx for a colleague. Check important ID columns in the preview before saving.