LangGraph is an open-source framework from LangChain for building stateful multi-agent systems using a directed graph model where nodes represent LLM calls or tools and edges define control flow. It gives developers fine-grained control over agent behavior, including human-in-the-loop checkpoints, persistent memory across sessions, and native token streaming. A hosted deployment service (LangGraph Platform) is available through LangSmith for teams that do not want to manage their own infrastructure. It is widely used for production agentic applications requiring reliability and auditability. Key features: - Graph-based workflow definition with explicit state transitions and control flow - Human-in-the-loop support with easy moderation checkpoints - Persistent memory and conversation history across sessions - Native token-by-token streaming of agent reasoning and actions - Multi-agent and hierarchical agent architectures in one framework - Hosted deployment via LangGraph Platform (managed on LangSmith)
LangGraph framework: free (MIT open source). Hosted LangGraph Platform: Developer tier free (100k nodes/month). Plus requires LangSmith Plus at $39/seat/month plus ~$0.001/node executed. Enterprise: custom.