LlamaIndex

LlamaIndex (formerly GPT Index) is a data framework for connecting LLMs with external data sources. It specializes in data ingestion, indexing, and querying for building context-augmented LLM applications. Key features include data connectors for 100+ data sources, document parsing and chunking, vector indexing and storage, retrieval strategies for semantic search, query engines for natural language queries, agents for multi-step reasoning, memory management for chat applications, integration with all major LLMs, evaluation tools for RAG systems, and production-ready components. LlamaIndex is widely used for building RAG applications, document Q&A systems, knowledge bases, research assistants, and intelligent search engines that combine LLMs with private or domain-specific data.