Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Does freak have negative connotations when it's used to describe a person who's very or overly interested in something?
Like football freak or coding freak.
Once again it depends upon context. There is not much negative implications for the two examples you cite, but in other cases, such as "control freak", there might be. And it's a descriptor which is probably best used in less formal contexts.
It is the seventh meaning listed for freak in the OED (sense 4d). An alternative word is aficionado.
There is no suggestion of it being negative.
Required, but never shown