The following sites provide a series of open source tools, scripts, plugins, and other resources developed over the past decade for the AEC design space.
neoarchaic
neoarchaic is a legacy site housing a range of scripted tools for Grasshopper 3d developed over the past decade
Interop.xyz
Developer website for open source and academic projects.
GitHub
Open source project repos
Food4Rhino
Grasshopper 3d Plugins available at McNeel's Food4Rhino website