Originally Posted By: andy
...

It appears to use main Yahoo!'s search data, with extra sources added in.
https://en.m.wikipedia.org/wiki/DuckDuckGo

Quote:
DuckDuckGo's results are a compilation of "over 400" sources,[14] including Yahoo! Search BOSS; Wolfram Alpha; Bing; Yandex; its own Web crawler (the DuckDuckBot); and others.[4][14][15][16] It also uses data from crowdsourced sites, including Wikipedia, to populate knowledge panel boxes to the right of the results.