Cracking the Code interview-style questions are what we are currently using. I'm not sure if that's where they originated, but that's the style of question. I think the key at my current gig is that engineers who interview regularly do the interview challenges. This ensures that the questions are reasonable to ask, and that effective guidance can be given to candidates.

For those without large engineering staff, HackerRank is good, in my experience. I use it for practice. I've had bad experience with leetcode, we used it at another place I worked and some of the crowd sourced questions were wrong.