mtCellEdit is a lightweight spreadsheet program. Its main goal is to provide facilities for simple day-to-day tasks using a minimal graphical user interface. It uses TSV based file formats to ensure that archived data is always accessible to other programs, regardless of operating system, both now and in the future. These "other programs" might be spreadsheet programs, text editors, command line tools, or custom built programs. It is written from scratch and provides all of its core facilities via a library, so any C program can access its API.