I'm thinking about joining this startup and want to hear if you think the product is nice to have or a must (it's free) - thanks!

I would greatly appreciate anyone willing to try this out and let me know your thoughts on their potential - thanks!!

Leaning towards a nice-to-have. The website could be better at explaining the product - needs more case studies in action. What’s their current audience size? Are they showing growth MoM in users? How’s burn rate? what’s on the product roadmap? — all questions I’d try to answer before joining. If their responses are all fantastic and they’ve found product-market fit, amazing!!
You need to watch a video by Craft ventures on the current Saas fundraising market and ask yourself if their metrics meet the criteria needed for the harsh winter coming to Saas start-ups. YOU think they will be able to raise more money?This is a super niche product so it's not something I am interested in. Maybe people in sales will find it interesting. I agree with the other commenter it looks like a 'nice to have'. Like if a person in sales can't be bothered to research prospects an app won't help. But I am not in sales so I don't know.And, is the market big enough is the other question.
My take on this is the most likely people to have the problem it solves are the inside sales people who have to make calls all day long. For those, the ability to get some quick information about each prospect could be very valuable. Their managers or a sales ops team would be the decision makers since the actual reps typically follow a prescribed process using well defined technology. If this product demonstrates it increases the success of their calls by a measurable percent, I’m pretty confident they would buy it. However that would need to be quantified. It would be good to find out how far along the company is in working through this process of figuring out how to close on early customers and prove the idea. Of course there are a lot of other factors in deciding about whether to join the company, like whether you believe they can execute.