Open-source alternatives to Langchain

LangChain is itself an open-source (MIT-licensed) framework for building LLM applications, so "alternative" here usually means a different approach to the same problem — either a lower-code visual builder instead of writing Python or JavaScript, or a framework built around a different abstraction, like persistent agent memory instead of chains and tools.

If you want a visual, drag-and-drop way to compose LLM pipelines instead of writing code, Flowise AI sits on top of LangChain-style concepts but removes the need to write glue code. If your focus is agents that need to remember state across long-running sessions rather than one-off chains, Letta is built specifically around persistent agent memory.

FAQ

Is there a free, open-source alternative to LangChain?

Yes. Letta and Flowise AI are both open source and free to self-host.

What's the best open-source alternative to LangChain?

Flowise AI is the better pick if you want a visual builder instead of writing code. Letta is the better pick if persistent, stateful agent memory is the core requirement.

Can I build LLM agents without writing code as a LangChain alternative?

Yes. Flowise AI provides a drag-and-drop interface for building LLM pipelines and agents, unlike LangChain's code-first approach.

What are the top open-source alternatives to LangChain?

Browse all open-source alternatives to LangChain above, or explore the full Developer Tools category for more options.