4D - 4D is a relational database management system and IDE.
Open Peeps - A hand-drawn illustration library.
LiveCode Platform - It is Both Under the GPL and it is also Proprietary if using the GPL version the software you make...
Control Illustrations - 108 free flat illustrations with customizable characters
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).
DrawKit - MIT licensed SVG illustrations, in 2 styles