Drop a legacy .xls file — the binary format Excel used up to 2003. Most files still in that format are exports from line-of-business systems that were never updated, which is also why they tend to contain data nobody wants to upload.
How XLS differs from XLSX
Files that are not really XLS
.xls" files in the wild are not XLS at all. Systems that generate reports very often emit an HTML table or a tab-separated file and name it .xls, because Excel opens it anyway. If that is what you have, this tool tells you so explicitly instead of producing an empty result — and the fix is usually to use the CSV tool directly.What a spreadsheet cannot bring with it
Other names for this
Also searched as “old excel to csv”, “convert xls to csv”.
Questions
- It says my file is plain text, not a spreadsheet.
- Then it genuinely is. Some reporting systems emit HTML or TSV with an .xls extension. Open it in a text editor to see which, then use the matching tool.
- Accented characters look wrong.
- They should not — the codepage recorded in the file is honoured. If they still look wrong, the file itself declares the wrong codepage, which happens with some older exporters.
- Is my data uploaded anywhere?
- No. The conversion runs as JavaScript inside this tab. Open your browser's Network panel and convert something — you will see no request carrying your data, because there is no server to send it to. You can also turn your Wi-Fi off and convert anyway.