What is LangChain?
LangChain is an open-source framework for building applications powered by large language models, providing modular components and abstractions for common LLM application patterns. It offers pre-built implementations for chains (sequences of LLM calls and logic), agents (autonomous decision-making systems), memory management, document loading and processing, and integration with various LLM providers, vector stores, and external tools.
The framework's component-based architecture allows developers to compose sophisticated LLM applications from reusable building blocks. Core concepts include prompt templates for consistent prompt construction, chains for multi-step workflows, agents that can use tools and make decisions, memory modules for maintaining state across interactions, and callbacks for monitoring and debugging. LangChain supports both Python and JavaScript/TypeScript implementations.
LangChain has become one of the most popular frameworks for LLM application development, with a large ecosystem of integrations, extensive documentation, and active community. It's particularly well-suited for building RAG systems, conversational agents, document analysis pipelines, and autonomous agents. While its breadth of features offers flexibility, developers often need to navigate complexity when building production systems. LangChain continues to evolve rapidly, with related projects like LangSmith for monitoring and LangServe for deployment.