LangChain

framework active open-source

A framework for developing applications powered by language models. LangChain provides modular abstractions for building chains (sequential LLM calls), agents (LLM-driven decision loops), RAG systems (retrieval + generation), and memory (conversation and long-term). It's designed to make LLM application development more composable and less boilerplate-heavy.

Implements

Concepts this tool claims to implement:

  • Agent Orchestration primary

    AgentExecutor class, create_react_agent, create_openai_functions_agent, and other agent factory functions. LangGraph (companion library) extends this with graph-based agent workflows.

  • Retrieval-Augmented Generation primary

    Retriever abstractions, vector store integrations (Chroma, Pinecone, Weaviate, etc.), document loaders, text splitters, and retrieval chains.

  • Tool Binding primary

    Tool and StructuredTool classes for defining tools. @tool decorator for easy tool creation. Tool schemas compatible with OpenAI function calling format.

  • Prompt Template secondary

    PromptTemplate, ChatPromptTemplate, and related classes for structured prompt construction with variable interpolation.

  • Agent Memory secondary

    ConversationBufferMemory, ConversationSummaryMemory, and various memory classes for maintaining state across interactions.

Integration Surfaces

  • Python SDK
  • JavaScript/TypeScript SDK
  • LangServe (deploy as REST API)
  • LangSmith (observability platform)
  • LangGraph (graph-based workflows)

Details

Vendor
LangChain Inc.
License
MIT
Runs On
local, cloud, hybrid
Used By
human, agent, system

Links

Notes

LangChain is one of the most widely adopted LLM application frameworks. It has evolved significantly since its 2022 launch, with LangGraph now handling more complex agent patterns. The ecosystem includes LangSmith for observability and LangServe for deployment.

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