Search by Jina.ai (demo: https://search.jina.ai/ and documentation: https://github.com/jina-ai) is a search engine with reasoning based on a series of dedicated models.

The research is preceded by a more or less long moment of reasoning of the model according to the chosen parameters with questioning from more than 100 sources.

Three levels of “depth” of reasoning and up to 3 search agents can be mobilized. An exclusive search mode on arxiv.org is also available.

Open source, free, no accounts, and seems unlimited.