Chat LangChain is LangChain’s official open-source question-answering agent for its own documentation. The repository has about 6,500 stars on GitHub and was actively maintained in 2026, and the live deployment answers developer questions at chat.langchain.com.
Built by the LangChain team as both a product and a reference implementation, Chat LangChain shows how to build a production documentation assistant. It is powered by Managed Deep Agents and retrieves answers from the LangChain documentation through MCP-based search, with a Pylon support knowledge base as a second source for troubleshooting questions. Answers are kept trustworthy with link verification, so cited pages actually exist, and guardrails keep the assistant focused on its documentation scope instead of wandering off topic. A Next.js frontend is included, making the repository a complete template for teams that want the same experience over their own docs. Because it is the team’s own support surface, the repository doubles as a public record of how LangChain itself builds agents: the retrieval design, evaluation habits, and deployment choices are all visible in the open, and developers frequently study it before designing their own support or documentation assistants.
Chat LangChain is free and open source under the MIT license, and the hosted chat at chat.langchain.com is free for anyone to use.
LangChain developers who want fast, cited answers about the framework, and engineering teams looking for a proven blueprint for a documentation chatbot of their own.