Is Coinbase legal in the US?

I'm curious about the legality of Coinbase in the United States. Could you please clarify whether it's a legitimate platform for cryptocurrency transactions? I've heard different opinions about it, and I'm seeking a professional opinion from someone like you who has deep knowledge in this field. Coinbase seems to be quite popular, but I want to make sure it's safe and legal to use in the US before I proceed with any transactions. Could you shed some light on this matter? Your insights would be greatly appreciated.