langchain-ai/langchain

Provides unified abstractions for LLM models, embeddings, vector stores, and retrieval tools across 100+ provider integrations, enabling seamless model swapping and real-time data augmentation. Built on a modular, component-based architecture that supports chains and orchestration patterns, with optional integration to LangGraph for complex agentic workflows and LangSmith for observability and evals.

129,354 stars and 225,878,213 monthly downloads. Used by 273 other packages. Actively maintained with 228 commits in the last 30 days. Available on PyPI.