PDFAITools
LlamaIndex
Data framework for building LLM applications with custom data. Connects LLMs to external data sources for RAG applications.
What is LlamaIndex?
What is LlamaIndex?
LlamaIndex is a data framework for building LLM-powered applications over custom data. It provides the tools to ingest, index, and query documents, databases, APIs, and other data sources, enabling developers to build Retrieval-Augmented Generation (RAG) systems with minimal boilerplate.
Key Abstractions
- Data Connectors: Load data from 100+ sources including PDFs, databases, Notion, Slack, and more
- Indexes: Structure data for efficient retrieval — vector indexes, keyword tables, knowledge graphs
- Query Engines: Sophisticated retrieval and synthesis pipelines
- Agents: LLM-powered agents that use tools built on top of your data
Use in Production
LlamaIndex is widely used in production RAG systems, enterprise search applications, and AI assistants. Its extensive integrations with vector databases (Pinecone, Weaviate, Chroma), LLM providers, and data sources make it a versatile foundation for any knowledge-intensive AI application.
Key Features
Ingest data from PDFs, databases, APIs, Slack, Notion, and dozens more.
Choose from vector, keyword, tree, and knowledge graph indexes.
Hybrid search, re-ranking, and query routing for high-quality retrieval.
Build agents that reason over your data with tool use and multi-step planning.
Swap any component — LLM, embeddings, vector store — without rewriting pipelines.
Who Uses LlamaIndex?
Build chatbots that answer questions over large document collections accurately.
Index internal knowledge bases and make them queryable with natural language.
Let users ask questions over structured and unstructured data in natural language.
Create agents that retrieve information and take actions using your company's data.
Pros & Cons
✅ Pros
- Best-in-class data connectors covering virtually every source
- Extremely flexible and modular architecture
- Active development with frequent new features
- Comprehensive documentation and tutorials
- Free and open-source core library
❌ Cons
- Rapidly evolving API can cause breaking changes between versions
- Performance tuning RAG pipelines requires significant experimentation
- Some advanced features require LlamaCloud (paid)
- Can be overly complex for simple single-document Q&A use cases
LlamaIndex Pricing
Open Source
- Full framework
- All connectors
- Self-hosted
- Community support
LlamaCloud
- Managed parsing
- Hosted indexes
- Enterprise connectors
- Priority support
LlamaIndex earns a 3.7/5 rating from our editorial team. It's completely free to use with no hidden costs, making it one of the most accessible tools in the AI Tools space. Standout strengths include best-in-class data connectors covering virtually every source and extremely flexible and modular architecture.
Get Started with LlamaIndex →