Ahrefs is the newest entry into the link research tool space.
They use their own bot and their own index (which they state is based on information from a trillion website connections).
Ahrefs Group Buy ($10 Only)
They claim their index is updated every 30 minutes and the fresh data is available to their users within 30 minutes of the actual index refresh.
Ahrefs also has a ranking database of roughly 45 million keywords from 9 different countries (US GB FR RU DE ES IT AU BR). The tools within their membership are:
- Site Explorer
- SERPs Analysis
Their pricing is very straight-forward and only increases or decreases based on volume of data you have access to.
You can check out the easy to understand pricing on their pricing page
(and they offer SEO Book readers a 50% discount on the first month).