Build a Local RAG Chatbot in 30 Minutes with .NET 8, Ollama, and React

Short summary

Build a privacy-first, cost-free PDF Q&A chatbot running entirely on your laptop using .NET 8, Ollama (free local LLM), and React—no cloud dependencies, no API costs, no data exposure. The author explains the limitations of cloud-based approaches (hallucinations, privacy risks, $45/month per user) and demonstrates RAG architecture with word-based chunking and overlap handling. Complete implementation with architecture diagrams, actual code examples, and a working repository.

• •Avoid privacy leaks and API costs ($45/month per seat) by building locally
• •Word-based chunking with 50-word overlap prevents answers from spanning chunk boundaries
• •Full stack: .NET PDF parser, Ollama embeddings (nomic-embed-text), in-memory vector store, React frontend—no external services

Generated with AI, which can make mistakes.