What framework to use to build an open-sourced LLM chatbot which is enterprise scalable to multiple users

Hey guys, what framework or tools do I use if I wanted to build an open-sourced LLM chatbot which is enterprise scalable to multiple users?

A framework/tool I am thinking of is Langchain. There won’t be any fine-tuning for my chatbot so I am not sure if I need to use Langchain.

Would there be a different suitable framework to use if I wanted to build for a small to mid sized enterprise compared to a large enterprise?

I am thinking of using AWS to host the LLM model.

Any help would really be appreciated. Many thanks!