Eight databases is a real answer
Searching arXiv, PubMed, OpenAlex and Crossref at once solves a genuine problem, because a researcher who checks only one of them misses work. ChatAcademia does that, adds grant sources, and reports 26,000 active users, which is more validation than most tools in this list can show.
It also inherits what those databases hold, which is metadata and abstracts. That is enough to find a paper and not enough to quote one.

