I Built a PDF Q&A App with RAG, FAISS, and Llama 3.1 — Here's Everything I Learned

TL;DR: I built an end-to-end RAG application that lets you upload any PDF and chat with it. It uses FAISS for vector search, sentence-transformers for embeddings, and Llama 3.1 via Groq for free LLM inference. This article walks through the full architecture, every bug I hit, and how to build it yourself. Why I Built This I was working through a Machine Learning course final project and kept running into the same problem: I had dozens of research papers and lecture notes as PDFs, and finding spe