Goodness no! Obviously your employer owns whatever you create while on the job, but some companies try to lay claim to stuff you create while off work, others do not.
The problem with Amazon - and other giant companies like it - is that they try to lay claim to everything "substantially similar" to fields the company works in. Because they're a giant company, this means practically everything, so you can work on something completely independently, without using any proprietary knowledge, and still end up screwed because somewhere deep within the bowels of the company someone is working on something like it.
In fact, in a number of states, agreements like that are unenforceable and invalid (California and Minnesota being 2 such states).
I can write code at home in my free time and it's MINE and I OWN IT.
It's a little like hiring a carpenter and then telling him that he can't make his own cabinets for his kitchen because the company owns everything he makes. Fuck that. I'll never work for a company that does that shit.
