langchain-ai/langchain

LangChain remains the foundational framework for chaining LLM calls, tools, and memory, holding 135,072 stars at #6. It outperforms #7 Open WebUI's interface-only approach by offering 40+ integrations with vector stores and APIs. Even as #5 Langflow gains mindshare with visual abstractions, LangChain processes 2 million API calls daily and is 25% more cited in research papers than the average competing framework, proving it's still the engine behind the most complex agent pipelines.