FlexiSheet - FlexiSheet is a multi-dimensional spreadsheet in the spirit of Lotus Improv.
Resolver One - Resolver One is a program that blends a familiar spreadsheet-like interface with the powerful...
Excel Formula Beautifier - Beautifies Excel to JavaScript/JSON format.
LibreOffice - Calc - LibreOffice Calc is the spreadsheet program you've always needed. A fork of OpenOffice.
EtherCalc - EtherCalc is a web spreadsheet.
Calligra Sheets - Calligra Sheets (formerly KSpread) is a fully-featured calculation and spreadsheet tool.