Research Tools for Digital Sleuths – This is largely focused on researching the “Deep State” and it looks like it has some good tools. And check out the “Partner Sites” at the left.
DuckDuckGo is only partly open source as of mid-2018 and has partnerships and uses technology from Google maps and so forth. “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.” (Duck Duck Go)