How to open and convert spreadsheets
- Drop an Excel file (.xlsx or .xls), an OpenDocument spreadsheet (.ods), a CSV or TSV file, or a JSON file. You can also paste CSV or JSON.
- Browse the data in a table; switch between worksheets with the tabs above it.
- Download the current sheet as CSV or JSON, or the whole workbook as a fresh .xlsx file.
Tick First row is a header to use it for column names (and JSON keys). Choose a semicolon separator for CSV files that will be opened in Excel in countries that use a decimal comma, such as Germany and France.
How it works
Modern Excel files (.xlsx) are ZIP archives of XML documents. This viewer unpacks them with your browser's built-in decompression, reads the shared strings, cell values and date formats, and shows the result, all without uploading anything and without loading any third-party library. Dates are shown as ISO dates (YYYY-MM-DD). Formulas show their last calculated value, as stored in the file. Older binary .xls and .ods files are read with the open-source SheetJS library, which is fetched only when needed.
The Excel files it creates are standard .xlsx workbooks with one sheet per tab, numbers stored as numbers and a bold header row, so they open in Excel, Google Sheets, Numbers and LibreOffice. CSV downloads include a UTF-8 marker so accented characters display correctly in Excel. Formatting, charts and formulas are not carried over when converting.
Is my spreadsheet uploaded?
No. It is read and converted entirely in your browser, so it is safe for confidential data.
Why do accented characters look wrong in my CSV?
Downloads include a UTF-8 byte-order mark that Excel uses to detect the encoding. If you created the CSV elsewhere, open it here and download it again.
How many rows can it handle?
Hundreds of thousands, limited by your device's memory. The table shows the first 1,000 rows, but downloads include everything.