---
description: Use LangChain Python packages to build AI applications on Cloudflare Workers.
title: Langchain
image: https://developers.cloudflare.com/og-docs.png
---

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# Langchain

Last updated Aug 24, 2026|Copy as Markdown|[View as Markdown](https://e8aee267.previews.developers.cloudflare.com/workers/languages/python/packages/langchain/index.md)|[Agent setup](https://e8aee267.previews.developers.cloudflare.com/agent-setup/)

[LangChain ↗](https://www.langchain.com/) is the most popular framework for building AI applications powered by large language models (LLMs).

LangChain publishes multiple Python packages. The following are provided by the Workers runtime:

* [langchain ↗](https://pypi.org/project/langchain/) (version `0.1.8`)
* [langchain-core ↗](https://pypi.org/project/langchain-core/) (version `0.1.25`)
* [langchain-openai ↗](https://pypi.org/project/langchain-openai/) (version `0.0.6`)

## Get Started

Clone the `cloudflare/python-workers-examples` repository and run the LangChain example:

```bash
git clone https://github.com/cloudflare/python-workers-examples
cd 05-langchain
uv run pywrangler dev
```

### Example code

```python
from workers import WorkerEntrypoint, Response
from langchain_core.prompts import PromptTemplate
from langchain_openai import OpenAI

class Default(WorkerEntrypoint):
    async def fetch(self, request):
        prompt = PromptTemplate.from_template("Complete the following sentence: I am a {profession} and ")
        llm = OpenAI(api_key=self.env.API_KEY)
        chain = prompt | llm

        res = await chain.ainvoke({"profession": "electrician"})
        return Response(res.split(".")[0].strip())
```

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