langchain
VerifiedFramework for building LLM agents and applications with modular components.
What is langchain?
LangChain is an open-source framework that helps developers assemble LLM-powered applications and agents from reusable parts. It supplies standard interfaces for chat models, embeddings, vector stores, and external tools while supporting many third-party providers.
Applications are built by combining these components into chains or more advanced workflows. LangGraph extends the core library for stateful agent orchestration, and LangSmith adds evaluation and observability when needed.
The project targets Python and JavaScript developers who want to prototype quickly yet retain control over model choice and data connections as their systems mature.
Capabilities
What you can build with langchain
Data-connected chatbots
Link language models to live databases or APIs so responses reflect current information rather than training data alone.
Model experimentation
Swap between providers during development to compare quality, cost, and latency without changing surrounding code.
Agent workflow design
Use LangGraph to create agents that plan, call tools, and maintain state across multiple steps.
Install langchain
uv add langchainuv add langchain- 1Run 'uv add langchain' to install the package.
- 2Import init_chat_model from langchain.chat_models.
- 3Create a model instance with a provider string such as 'openai:gpt-5.5'.
- 4Call model.invoke with a prompt to receive a response.
- 5For complex agents, install LangGraph and define stateful workflows.
langchain: pros & cons
Pros
- +Wide range of model and tool integrations that stay consistent across providers
- +Clear separation between high-level chains and low-level components
- +Strong ecosystem including debugging and deployment utilities
- +Active community that contributes new integrations and examples
Cons
- –Core library alone does not include full agent runtime features
- –Abstraction layers can add indirection that complicates simple scripts
- –Performance and reliability still depend on the chosen LLM provider
Frequently asked questions
No, an equivalent library exists for JavaScript and TypeScript.
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