mtCellEdit is a lightweight spreadsheet program that I created from scratch. It is a small, no frills program which is designed to handle simple day to day spreadsheet tasks. I have put the most important facilities I want into a small customized program which means I can avoid the problems of larger programs such as slow operating speeds and overcomplicated user interfaces. The GUI is presented using Qt4, or Qt5 (whichever you prefer).
The core of the program is a shared C library which can be used by any C program to read, write and manipulate spreadsheets. The source code suite also contains other example programs that use this library, such as command line tools to allow scripts to access the API.
The default file format mtCellEdit uses is portable and transparent as it is a ZIP file containing TSV text files. I deliberately designed it this way so that data can be extracted and read by any modern spreadsheet program on any operating system without requiring mtCellEdit. Over the years I have been frustrated by binary and XML formats that make data only accessible via a single program (or by me wasting time manually converting each file, or by me writing a file format conversion program). This format ensures that my data never becomes stranded, and can be manipulated by whichever tool I choose for a particular job (i.e. spreadsheet programs, text editors, command line tools, etc).
mtCellEdit is designed for GNU/Linux operating systems. Hardware wise it has been tested on x86_32, x86_64, ARM and PowerPC platforms.
The source code is distributed under the GNU General Public License version 3 or later. Read more about this here https://www.gnu.org/copyleft/gpl.html
As well as the mtCellEdit program, the source code archive also contains a suite of other programs which use the core spreadsheet libraries:
A GUI based program to study the results of UK General Elections from 1945-2015.
A GUI based program to study the contents of directories.
A collection of command line tools for working on text based spreadsheets (i.e. TSV and CSV files).
An interactive command line program for manipulating spreadsheets. The functions available are identical to mtCellEdit but accessed using a command line interface (via GNU readline).
A very basic command line network activity logger.
A command line program that creates files of random data (e.g. passwords, matrices, and binary one time pads).