LlamaIndex is a data framework designed to facilitate the integration of private or domain-specific data with large language models (LLMs). It offers tools for ingesting data from diverse sources — including APIs, databases and PDFs — and structures this data into a format that LLMs can easily consume. Through various types of "engines," LlamaIndex enables natural language interactions with this structured data, making it accessible for applications ranging from query-based retrieval to conversational interfaces. Similar to LangChain, LlamaIndex’s goal is to accelerate development with LLMs, but it takes more of a data framework approach.