What are some alternatives?
When comparing EtherCalc and Apache OpenOffice Calc, you can also consider the following products
Google Sheets - Synchronizing, online-based word processor, part of Google Drive.
LibreOffice - Calc - LibreOffice Calc is the spreadsheet program you've always needed. A fork of OpenOffice.
Apple Numbers - Numbers lets you build beautiful spreadsheets on a Mac, iPad, or iPhone — or on a PC using iWork for iCloud. And it’s compatible with Apple Pencil.
Microsoft Office Excel - Microsoft Office Excel is a commercial spreadsheet application.
Gnumeric - Gnumeric
Zoho Sheet - Create and share interactive spreadsheets on the web.