Referring domains your competitor has and you do not, ranked by authority so you work the twenty that matter instead of the four hundred that don't.
Every other tool on this site works by fetching your page and analysing it. We can do that for free because the only cost is a few seconds of compute.
Backlink data is different in kind. Knowing who links to a domain means having continuously crawled a large fraction of the entire web and kept an index of it. Four or five companies in the world do that, and they sell access to the index — that is the whole business. There is no free API, no clever workaround, and no public dataset that is current enough to be useful.
So this tool is built as an adapter. Connect a provider and it returns real data. Without one it tells you that, plainly, and shows you nothing.
Focus on the gap domains that already link to several competitors but not to you, and ask whether you have a reason to be mentioned there. Pair this with the Unlinked Mention Finder for the easier wins, and track competitor changes over time with Watchdog. For help prioritizing, see our AEO/GEO consulting.