5 Best RAG Frameworks in 2026: LangChain vs LlamaIndex vs Haystack Compared
RAG frameworks (Retrieval-Augmented Generation frameworks) have become essential for building production-grade AI applications in 2026. The best RAG frameworks—LangChain, LlamaIndex, Haystack, DSPy, and LangGraph—enable developers to combine large language models with domain-specific knowledge retrieval. When comparing LangChain vs LlamaIndex vs Haystack, key factors include token efficiency, orchestration overhead, and document processing capabilities. Performance benchmarks reveal that Haystack achieves the lowest token usage (~1,570 tokens), while DSPy offers minimal overhead (~3.53 ms). LlamaIndex excels for document-centric applications, LangChain provides maximum flexibility, and Haystack offers production-ready pipelines. Understanding RAG framework architectures is critical for developers building knowledge bases, chatbots, and retrieval-augmented generation systems. ...