"front-end" only applies as an adjective to some thing like "front-end developer" though, "frontend developer" is pretty well accepted. Talking about a front end (noun) means there's no need for a hyphen. See this discussion for a full breadth of usage guideline POVs. https://english.stackexchange.com/questions/34447/is-it-front-end-frontend-or-front-end
Tim Hockin