From my article How to Avoid Funding the American Deep State:

"The only decent open-source and privacy-respecting search engines I know of are Searx and YaCy. Searx avoids big bills by aggregating the results of other search engines, and Yacy does it by being peer-to-peer.

As for why I don't recommend using DuckDuckGo: it's only partly open-source, it displays Yahoo!-Microsoft search alliance ads (ads can be disabled), it partnered with Yahoo! (which owns Tumblr) to get access to tech and features, and it makes use of Google Maps, Apple Maps, Bing Maps, and Here WeGo. To be fair, DuckDuckGo also gives you the option to use maps from the OpenStreetMap project.
(DuckDuckGo earns money via its affiliate program with Amazon and eBay - it says the program doesn't influence its rankings or relevancy functions in any way, but, after all, DuckDuckGo isn't open source.)"