Convert Excel files to CSV
Supports workbooks up to 150,000 rows (including the header row, files up to 90 MB). Conversion runs in the background — this tab stays responsive.
Click or drop an Excel file here
Excel to CSV reads an uploaded .xlsx or .xls file using the xlsx library and converts its first sheet to comma-separated CSV text, entirely in your browser — your file is never uploaded to a server. Reading and parsing run off the main thread in a Web Worker, so the page stays responsive even on large files, and the result downloads automatically as a .csv file. Only the first sheet is converted; there's no sheet picker for workbooks with multiple sheets, and no delimiter options beyond a standard comma.
Is my file uploaded to a server?
No, the conversion happens entirely in your browser using the xlsx library, in a background Web Worker so the page never freezes.
Can I choose which sheet to convert?
No — only the workbook's first sheet is converted; there's no sheet selector.
Why is there a row and file-size limit?
Excel files can't be parsed incrementally the way plain text can, so converting a very large workbook risks the tab running out of memory or taking too long. Uploaded files are capped at 150,000 rows and 90 MB on desktop, measured to convert reliably.
Will formatting like colors or fonts carry over?
No, CSV is plain text, so only cell values transfer — formatting, formulas' calculated results (not the formulas themselves as text), and structure like merged cells don't.
Can I download the CSV as a file, or is it only shown on the page?
It downloads automatically as converted.csv — there's no inline preview, since a large workbook's CSV output can be too big to safely render on the page.