Serpstat is a cloud-based All-in-One SEO platform for professionals. It includes 5 essential tools: position tracking, backlink analysis, competitor analysis, site audit and keyword research.
Their query based pricing makes the product almost unusable. They'll charge you for every DB query they post -- every click will cost you the number of DB queries that action requires. That's pretty random and dependent on how efficiently they do that (I don't see much incentive to optimize that). Moreover, reports you "purchase" are not cached i.e if you request the same report you just saw/purchased, you'll be charged again.
Pros:A lot of valuable analysis and reporting tools
Cons:Pricing
PageSpeed Ninja