Pandosearch provides a search as a service facility which allows you to just integrate the API to your website and make all your search related query resolved, all the complex search that happens in your website, pandosearch will do it for you. Review collected by and hosted on G2.com.

The only thing that I have disliked about Pandosearch is that when user uses natural language and do search, so it tries to convert the language but because of grammatical mistake the results differ. Review collected by and hosted on G2.com.