This is a backlink analyzer inside SEO SpyGlass, a tool that crawls all inbound and outbound links of a website, providing all important SEO metrics to estimate the site's link profile.
The backlink checker tool analyzes a website's backlink profile to discover risks and opportunities relates to links (which are a known Google ranking factor). The backlink analyzer helps detect spammy links, link farms, doorway pages, or, on the positive side, to find new linking opportunities, fresh domains in the niche with whom you can partner.
There is a free plan in SEO SpyGlass allowing you to analyze up to 1100 backlinks per website and compare 2 competitors. Also, you can try the online free backlink checker to do the same without the need to install any software.
SEO PowerSuite crawler works just like other web bots do, crawling URLs and all links coming in and out of them. As it starts from a seed set of web pages, it's a continuous process, with … new URLs being added to the index every minute.