Convert an Excel (.xlsx) workbook to CSV right in your browser, without launching Excel. Click "Open .xlsx" or drag a file onto the page, and it reads the worksheet, shows it as a table preview, and renders the contents as CSV that you can copy or download with "Download .csv". If the workbook has several sheets, pick which one to convert from the menu. Choose comma, semicolon, or tab as the delimiter, and if the CSV later shows garbled characters when reopened in Excel, turn on "Add UTF-8 BOM" so Excel detects the encoding correctly. Under the hood, an .xlsx file is really a ZIP of XML, so decompression, parsing, and CSV generation all happen inside your browser in JavaScript — your file is never uploaded, stored, or sent to a server. That makes it safe for customer lists, sales figures, or internal spreadsheets you'd rather not put on a cloud converter (and it suits workplaces where uploading files externally is against policy). Handy when you're on a machine without a spreadsheet app, you only need the CSV, or you want to skip opening Excel. Note: dates and times are stored in the sheet as Excel's internal serial numbers, so they come out as the stored value; formula cells output the cached calculated value saved in the file. Want to inspect the result as a table? Try csv-viewer, or csv-to-markdown to turn it into a Markdown table.