Free Open-Source Artificial Intelligence

Hey everyone.
I have some pdf-documents containing information. Is there a LLM/AI I could feed this into, and then ask questions, and the AI would answer with the information from the document, ideally with where to find it in there?
I have heard of tools called "chatPDF" (the name seems so clever that multiple sites use it), which seem to be doing exactly that. Unfortunately I don't want to upload these documents to some random website.
So I either need something like this that I could host myself (is something like that even feasible?), or an online service with good privacy/something where I could trust that the documents would not be used to train, or gather statistics etc.
Any help or pointers would be greatly appreciated!