LlamaIndex
Data framework for LLM applications: ingestion, indexing, retrieval, and agents over documents and APIs.
Why it is included
One of the two dominant OSS RAG/agent data layers alongside LangChain, with strong doc + structured data focus.
Best for
Python teams building production RAG with composable retrievers and query engines.
Strengths
- Indexing abstractions
- Observability hooks
- Multi-language
Limitations
- Rapid API evolution—pin versions in production
Good alternatives
LangChain · Haystack · Semantic Kernel
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