I was going to suggest Rive too. I came across them when I was trying to figure out how Duolingo's animations were done, pretty cool tool.
For Trangram - it might help to link each of the examples in the "Explore & Get Inspired" section to the editor, allowing new users to avoid the "blank page" syndrome.
It’s pretty much modern Macromedia Flash. Except a JS runtime, rather than plugin.