There’s also YaCy, which is a peer-to-peer search engine. You index whatever you want, and when you search, you connect to lots of other indices.

I want to set up my own node at some point. My understanding is that the search results are hit and miss, but you have the power to improve things by building your own index of pages you want to search regularly. And this benefits everyone else too.

Since search indexing is so intensive, I think it’s the right technical solution for a truly open alternative.