Are there search engines (like your own Google) for private (home) use?

Question

Yes, the topic title is loud enough and I don't need my own Google. I'm just looking for a solution for private use as part of a search on a list of specific sites.
Does anyone know about such software? To be highly productive, without the tinsel of features. That is spider + ranking + web interface + api. Preferably open source (ready to donate and add to turnips).
Some will think that it makes no sense to invent great, but in part. The fact is that I want to automate requests and they can reach up to 10 million per month, 2 million are always unique (caching does not solve it).
I can't use the search engine API:
1) a lot of extra sites
2) costs money (google and bing bend the price, yahoo even less)
I really need help! Thank you.

Answer 1

YaCy . Be prepared to allocate memory and disk space to it.

Answer 2

One of the best is Solr