You don't train on documents. There are many startups claiming that but they are deliberately using a misleading term because they know that's what people are searching for. You still do RAG. Llamaindex is still the best option that I know of. Most of the startups that have working products are likely using llamaindex. All of the ones that say they are training on documents are actually using RAG. Test it out. If it…
What is RAG? That's hard to search for
Retrieval Augmented Generation - in brief, using some kind of search to find relevant documents to the user’s question (often vector DB search, which can search by “meaning”, by also other forms of more traditional search), then injecting those into the prompt to the LLM alongside the question, so it hopefully has facts to refer to (and its “generation” can be “augmented” by documents you’ve “retrieved”, I guess!)