Google Scholar - Google Scholar is a freely accessible web search engine that indexes the full text of scholarly...
Klevu - Klevu offers instant site search solution for eCommerce stores.
Google Custom Search - Google Custom Search enables you to create a search engine for your website, your blog, or a collection of websites.
ResearchGate - Access scientific knowledge, and make your research visible
Swiftype Site Search - Swiftype Site Search helps to sell more, get the right answer to more people on the platform and surface relevant content for readers and followers.
Synthical - AI-powered collaborative research environment. You can use it to get recommendations of articles based on reading history, simplify papers, find out what articles are trending, search articles by meaning (not just keywords), and so on.