From what I understand, it's mostly Bing + Yandex (for Russian pages) these days - the additional sources are websites that submit their own custom indexing of their pages.
I suspect the nature of things just leads to that even if they have multiple big upstreams.
If bing offers up the best results most of the time DDG will, as a result, offer up bing results most of the time. "Best results" easily determinable even with DDG privacy constraints.
They're definitely doing some cool stuff at DDG and its certainly a hell of a lot more than "a wrapper around bing." I just don't think expanding their own index infrastructure is something feasible for them right now.
Sure, but I don't think it's fair to compare DDG to other search engines that crawl and index the entire web themselves. It's a different user experience for sure but the indexing is (for the most part) the same as Bing.
If bing offers up the best results most of the time DDG will, as a result, offer up bing results most of the time. "Best results" easily determinable even with DDG privacy constraints.
They're definitely doing some cool stuff at DDG and its certainly a hell of a lot more than "a wrapper around bing." I just don't think expanding their own index infrastructure is something feasible for them right now.