About

LlamaIndex is an open-source data framework designed for building applications that connect large language models with external data sources, with a particular focus on retrieval-augmented generation (RAG) and knowledge-grounded AI systems. Originally created by Jerry Liu in late 2022 under the name GPT Index, the framework has grown into one of the most widely used tools for building production RAG pipelines and LLM-powered data applications. LlamaIndex provides a comprehensive set of tools for ingesting data from over 160 sources including PDFs, databases, APIs, web pages, Slack, Notion, Google Drive, and many more through its LlamaHub connector ecosystem. The framework handles the complete RAG pipeline from data ingestion through indexing, retrieval, and response synthesis. Core components include document loaders and readers, node parsers for chunking and transforming documents, index structures for organizing data (vector, list, tree, keyword, and knowledge graph indices), retrievers for fetching relevant context, and response synthesizers for generating LLM responses grounded in retrieved data. LlamaIndex supports advanced retrieval strategies including hierarchical retrieval, recursive retrieval, fusion retrieval, auto-merging, and sentence window retrieval that go beyond simple vector similarity search to improve answer quality. The framework also provides agentic capabilities through LlamaIndex Workflows, enabling developers to build complex multi-step AI applications with tool use and reasoning. LlamaIndex integrates with all major LLM providers, embedding models, and vector stores. LlamaCloud is the companion managed service that provides managed ingestion and retrieval pipelines optimized for production use. The core framework is free and open-source under the MIT license, available in Python and TypeScript. LlamaCloud offers a free tier and paid plans starting at $399 per month for production workloads.

AI Agent Frameworks

LlamaIndex provides agentic capabilities through LlamaIndex Workflows and tool-use abstractions that enable LLMs to reason over data, make decisions, and execute multi-step tasks. Developers can build agents that combine retrieval with computation and external tool use for complex data-driven applications.

AI Data Analysis

LlamaIndex enables natural language querying over structured and unstructured data sources, allowing users to ask questions about their data and receive AI-generated answers grounded in the actual content. Its support for SQL, pandas, and knowledge graph indices makes it a powerful tool for AI-assisted data exploration and analysis.

AI MLOps Tools

Through LlamaCloud and its observability integrations, LlamaIndex supports production deployment and management of RAG applications. It provides evaluation tools for measuring retrieval and response quality, tracing integrations for debugging pipelines, and managed services for scaling data ingestion and retrieval in production.

AI Prompt Engineering

LlamaIndex provides prompt management tools and response synthesis strategies that help developers optimize how context is presented to LLMs. Its retrieval and synthesis pipeline offers fine-grained control over prompt construction, including techniques like tree summarization and compact prompting for handling large contexts.

AI RAG Tools

LlamaIndex is one of the leading frameworks specifically designed for building retrieval-augmented generation systems. It provides the complete RAG pipeline from data ingestion through 160+ connectors, advanced chunking strategies, multiple index types, sophisticated retrieval methods, and response synthesis, making it a comprehensive solution for grounding LLMs in custom data.

Tool Details Free

Pricing Free open-source (LlamaCloud: Freemium from $399/mo for production)
Platform Self-hosted, API
Headquarters San Francisco, CA
Founded 2022
Free Plan Yes
Open Source Yes
Enterprise Plan Yes
4.3 3 reviews

AI Reviews

🤖
4.2 /5

LlamaIndex is the gold standard for building RAG (Retrieval-Augmented Generation) applications, offering an exceptionally well-designed framework for connecting LLMs with custom data sources. Its data connectors (LlamaHub) support 160+ integrations, making ingestion from PDFs, databases, APIs, and more remarkably straightforward. The indexing and query engine abstractions are powerful yet intuitive, enabling developers to build sophisticated retrieval pipelines with minimal boilerplate.

The agent framework capabilities have matured significantly, though they trail slightly behind dedicated agent platforms like LangGraph in complex multi-step orchestration. Data analysis workflows benefit from structured output parsing and query engines over tabular data. Prompt engineering support is solid with customizable prompt templates, though it's more of a supporting feature than a core focus.

LlamaCloud adds managed parsing and indexing for production workloads, though the $399/mo starting price may deter smaller teams. The open-source core is exceptionally generous and well-documented. Active community, frequent updates, and excellent TypeScript/Python support make this an essential tool for any RAG-focused project.

Category Ratings

AI Agent Frameworks
4.2
AI Data Analysis
4.3
AI MLOps Tools
3.8
AI Prompt Engineering
3.9
AI RAG Tools
4.9
Feb 15, 2026
AI-Generated Review Generated via Anthropic API. This is an automated evaluation, not a consumer review. Learn more
🤖
4.5 /5

LlamaIndex stands out as the premier data framework for connecting Large Language Models (LLMs) to custom data sources. While it began as a vector store interface, it has evolved into a comprehensive ecosystem for building production-grade Retrieval-Augmented Generation (RAG) applications and autonomous agents. Its core strength lies in its sophisticated indexing strategies and data ingestion capabilities, making it arguably the best choice for developers focused on high-accuracy data retrieval.

The open-source library is incredibly robust, offering hundreds of loaders and integrations. However, the sheer volume of features can present a steep learning curve for beginners compared to simpler alternatives. While the core framework is free, the managed LlamaCloud service targets enterprise users with a higher price point for advanced document parsing and managed storage. For developers serious about building context-aware AI applications, LlamaIndex is an essential, industry-standard tool.

Category Ratings

AI Agent Frameworks
4.6
AI Data Analysis
4.5
AI MLOps Tools
4.2
AI Prompt Engineering
4.2
AI RAG Tools
5.0
Feb 15, 2026
AI-Generated Review Generated via Google API. This is an automated evaluation, not a consumer review. Learn more
🤖
4.3 /5

LlamaIndex stands as one of the most comprehensive frameworks for building RAG (Retrieval-Augmented Generation) applications. Its data connectors support 160+ sources, making ingestion remarkably flexible. The framework excels at indexing, querying, and structuring data for LLM consumption, with excellent documentation and an active community.

Strengths include its modular architecture, extensive integrations with vector databases, and robust query engines that handle complex retrieval patterns. The open-source core is genuinely powerful, allowing production-ready applications without cost.

Limitations include a steeper learning curve compared to simpler alternatives like LangChain for basic use cases. LlamaCloud's $399/month starting price for managed services may deter smaller teams. Agent capabilities, while improving, still lag behind dedicated agent frameworks.

Ideal for developers building sophisticated data-augmented AI applications who need fine-grained control over their retrieval pipelines. The ecosystem maturity and enterprise features make it a top choice for production RAG systems.

Category Ratings

AI Agent Frameworks
4.3
AI Data Analysis
4.4
AI MLOps Tools
3.9
AI Prompt Engineering
4.0
AI RAG Tools
4.8
Feb 12, 2026
AI-Generated Review Generated via Anthropic API. This is an automated evaluation, not a consumer review. Learn more