Llamaindex

LlamaIndex is the go-to framework when you need to connect LLMs to your own documents and data. It handles the full RAG pipeline: ingesting files through 300+ connectors, chunking and indexing them into vector stores, and querying with context. The API is refreshingly simple,five lines gets you from a folder of PDFs to a working Q&A system. It shines for document chatbots and knowledge retrieval over private data, with solid primitives for metadata filtering, chat history, and structured outputs. If you're building agents that need general tool use rather than document search, LangChain might be better, but for data-centric applications LlamaIndex is hard to beat. The 45k GitHub stars reflect real production use.