LlamaIndex is an open-source data orchestration framework for building production-ready LLM applications, specializing in retrieval-augmented generation (RAG) and agentic document workflows. It connects private or domain-specific data to large language models through sophisticated indexing, retrieval, and query mechanisms. Unlike general-purpose orchestration frameworks, LlamaIndex prioritizes data ingestion pipelines, advanced retrieval strategies, and context engineering — making it the go-to choice when your application's success hinges on how well you retrieve and structure information before passing it to an LLM. The framework treats documents as first-class citizens, offering deep control over chunking, embedding, metadata extraction, hierarchical relationships, and multi-step retrieval patterns that are essential for knowledge-intensive applications.