XLS Editor is an extension that allows to create, edit and view any Microsoft Excel document in both XLS and XLSX format. It also handles the standard Open Office format ODS. It is an integration with LibreOffice Online. XLS Editor main features are:

- A direct link to create xls, xlsx or off spreadsheets with this XLS Editor.
- Edit and view XLS spreadsheets written using OpenOffice Calc, LibreOffice Calc or Microsoft Excel.
- Styles management.
- Font sizes.
- Font colours.
- Background colours.
- Search for texts.
- Insert columns / rows / tables / images..
- Delete rows / columns.
- Advanced find & replace / regular expressions / special characters.
- Spreadsheet functions.
- Export to PDF.
- Auto save files.
- Open source code.
- Supports multiple formats for spreadsheets:
* Microsoft Excel 97/2000/XP (.xls)
* Microsoft Excel 4.x–5.0/95 (.xls)
* Microsoft Excel 2007 XML (.xlsx)
* LibreOffice ODF spreadsheet (.ods)
* OpenOffice ODF spreadsheet (.ods)
* Text and CSV (.csv and .txt)