How this tool works

You type a domain and the tool looks it up in Common Crawl's open web graph, a map of 118+ million domains and 4.3 billion links rebuilt every month. You get the domain's Harmonic Centrality and PageRank, each as a global rank (e.g. #676 out of 118M) and as a "top %", plus the number of hosts Common Crawl saw on it.

Harmonic Centrality measures how "close" a domain is to all other domains in the web graph: a domain with strong HC can reach many other domains through fewer link hops. Common Crawl uses it to prioritise its crawl and treats it as the primary, spam-resistant signal. PageRank measures a domain's authority based on the quantity and quality of links pointing to it, so being linked by other high-authority sites pushes it up. Both come straight from Common Crawl, 100% free and open, no API key. Lookups are instant because the latest release's top 12M domains are pre-loaded into a local database.