Connected Papers is described as 'Unique, visual tool to help researchers and applied scientists find and explore papers relevant to their field of work' and is a academic research tool in the education & reference category. There are more than 10 alternatives to Connected Papers, not only websites but also apps for a variety of platforms, including iPhone, SaaS, Mac and Windows apps. The best Connected Papers alternative is Google Scholar, which is free. Other great sites and apps similar to Connected Papers are Research Rabbit, Inciteful, ResearchGate and Litmaps.
Google Scholar does not provide visual graphs to explore relative papers.