This thread is aimed to collect opinions and information about (preferably free) tools to look for and discover insights on research literature.
I have used Semantic Scholar for searching literature. Nowadays I also use tools such as ConnectedPapers (connectedpapers.com) and Elicit (elicit.org) to get more insights on research topics. Research Rabbit (researchrabbit.ai) is also a favourite, though it takes time to load at times.
Connected Papers used to be free to use, but have now introduced cap on number of searches one can do in a month.