LangChain vs Letta

LangChain is a free, MIT-licensed open-source framework for building agents with models and tools. Its create_agent harness combines a model, tools, prompt and middleware, with templates for common uses and a ReAct pattern. Middleware can add human approval, conversation compression, sensitive-data removal, guardrails, retries, routing and custom tool policies. Agents run on LangGraph’s durable runtime, which supports persistence, rewind, checkpointing and human-in-the-loop workflows. LangChain documents more than 1,000 integrations across chat and embedding models, tools, toolkits, document loaders and vector stores. Standard interfaces for chat models and embeddings support switching providers with minimal code changes. Documentation covers Python and JavaScript/TypeScript. LangSmith adds tracing, debugging and output evaluation. The framework supports API and self-hosted use. LangChain was started in 2023 and is headquartered in San Francisco.

Letta has no write-up on Specifiction yet; its figures are above.