I think that definition of "senior level of expertise" is a bit too much for full-stack engineers. I actually have worked with many engineers who are very comfo

I think that definition of "senior level of expertise" is a bit too much for full-stack engineers. I actually have worked with many engineers who are very comfortable working front to back end creating wholistic solutions. To me, full stack engineer is someone who can design and implement a wholistic solution. If you can build a todo app, you're pretty much a full-stack engineer (a junior one and also depending on the todo app implementation).