QA
Beginner LevelAI, LLMs, Embeddings & MCP

Compare LangChain vs LlamaIndex frameworks for building LLM applications.

❓ Interview Prompt: Compare LangChain and LlamaIndex regarding data ingestion, RAG abstractions, and agent orchestration.

1. LangChain:

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Focus: Generic application orchestration and multi-step agent workflows.
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Strengths: Extensive integration ecosystem (hundreds of tools, memory stores, models), flexible chain compositions, and agent execution loops.

2. LlamaIndex (formerly GPT Index):

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Focus: Specialized Data Ingestion and RAG Search Retrieval.
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Strengths: Advanced document parsing (LlamaParse), hierarchical index structures, sub-question query engines, and out-of-the-box RAG optimization.

Modern Paradigm (2026):

Developers frequently combine both: using LlamaIndex for RAG ingestion/indexing and LangChain or custom TypeScript code for agent orchestration.

Code Implementation Example

typescript
// LlamaIndex: Quick RAG index creation over documents
import { VectorStoreIndex, SimpleDirectoryReader } from 'llamaindex';

const documents = await new SimpleDirectoryReader().loadData({ directoryPath: './data' });
const index = await VectorStoreIndex.fromDocuments(documents);
const queryEngine = index.asQueryEngine();
const response = await queryEngine.query({ query: 'What is our refund policy?' });
💡Creating RAG query engine using LlamaIndex.
🎯 Interview Key Takeaway

Use LlamaIndex for advanced RAG indexing and data retrieval; use LangChain for generic agent workflow orchestration.

#LangChain#LlamaIndex#Frameworks#RAG#Beginner
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