I want to build my own "second brain" with info and docs and be able to chat with it. Is this currently possible?

Is there a tool that does this? Essentially I want an AI I can chat with, which I can freely feed documents, information, contacts, etc, and then just chat with it to recover that information or ask it to interpret and provide insights on the information.

Ideally, I'd love to be able to do with a local LLM rather than connected to the internet.

artificial brain build chat documents etc information second brain tool