Wikipedia says DuckDuckGo generates "results from over 400 individual sources, including crowdsourced sites such as Wikipedia, and other search engines like Bing, Yahoo!, and Yandex." Even if it was just a proxy to the Bing Search API, DDG users would be unseen by Bing servers.

https://en.wikipedia.org/wiki/DuckDuckGo

No, in general it's not. https://duck.co/forum/thread/4350/did-you-know-that-duckduck...

IME, inline results from third party sites (like StackOverflow, images, youtube videos, etc.) are pretty easy to notice when they're included and easy to tell where they came from.

They cite Bing, Yahoo, and Yandex as "sourced from," and they do list DuckDuckBot as its own thing -- although I am pretty sure they don't have the same resources for running their own distributed crawls as the 3 sources they list:

https://duck.co/help/results/sources

DuckDuckBot only handles results for Instant Answers afaik. No own spiders in the traditional sense (following links between domains).

https://duck.co/help/results/sources says they have 400 sources which is special cases like Wikipedia,etc. The core search is powered by Bing (Yahoo uses Bing) and Yandex in Russia.

My guess is that it is mostly bing, a few percentages for other sources. They never share the breakdown. It would spoil their magic I suppose.