JuliaSmoothOptimizers (JSO) is an organization that I co-created with Dominique Orban around 2015 (or 14?) to store our optimization packages.
The main idea of our packages is to enable high-quality development of optimization solvers, and it now contains over 60 packages.
The main research area of JSO is nonlinear continuous optimization.
Originally we looked only into twice differentiable problems, although that is changing a bit now, with some more general packages.