The Abacus spreadsheet using C++ and Tcl-Tk.

Moodss (Modular Object Oriented Dynamic SpreadSheet) is a modular application. It displays data described and updated in one or more modules loaded at start-up. Data is originally displayed in tables. Graphical viewers, summary tables, and free text viewers can be created from any number of table cells.

Gnumeric is intended to be a replacement for a commercial spreadsheet. Part of the Gnome project.