Microsoft Office Access - Access is now much more than a way to create desktop databases. It’s an easy-to-use tool for quickly creating browser-based database applications.
RetroArch - RetroArch is a frontend for emulators, game engines and media players.
LiveCode Platform - It is Both Under the GPL and it is also Proprietary if using the GPL version the software you make...
Playnite - Source code generated using layoutit.com
ESM Tools - ESM Tools is a powerful and widely known software development platform that comes with a centralized model infrastructure, providing the common frame for compiling, running, downloading, and organizing models (ones or multiple).
Batocera.linux - Batocera.linux is an open-source and completely free retro-gaming distribution that can be copied to a USB stick or an SD card with the aim of turning any computer/nano computer into a gaming console during a game or permanently.