I agree with the article, LangChain is both fun and good technology (I am biased, my latest book is on LangChain - you can read it free at <a href="https://leanpub.com/langchain" rel="nofollow">https://leanpub.com/langchain</a> using the Free to Read Online link).<p>LlamaIndex is another library that facilitates building applications using OpenAI and Hugging Face APIs (and running local models). LlamaIndex and LangChain are useful together.<p>It is one thing to play with the ChatGPT web app (or mobile apps), but I think it is a better thing to write your own code to use your own text documents (and Google Docs, etc.).