L
Capabilities:chatcode
License:MIT
Open sourceLocal runtimeLangChain
About
A framework for building applications powered by LLMs — chains, agents, tools, memory and retrieval. The most popular toolkit for production LLM apps, with Python and JS versions.
Pricing
Free
LangChain is a framework for LLM application development. It provides composable abstractions for chains, agents, retrieval (RAG), memory and tool calling, plus integrations with hundreds of models and vector stores.
Key Features
- Chains and agents for complex workflows.
- RAG primitives with vector-store integrations.
- Tool calling and function binding.
- LangGraph for stateful, controllable agents.
- LangSmith for tracing and evaluation.
- Python and JavaScript/TypeScript packages.
Pricing
LangChain core is free and open source under MIT. LangSmith (observability) has a free tier with paid plans.
Getting Started
pip install langchain langchain-openai
from langchain_openai import ChatOpenAI
llm = ChatOpenAI(model="gpt-4o")
print(llm.invoke("Tell me a joke"))
Or in JS: npm install langchain @langchain/openai.