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

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/workers/llms.txt  
> Use this file to discover all available pages before exploring further. 

[Skip to content](#%5Ftop) 

# Langchain

[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:

Terminal window

```
git clone https://github.com/cloudflare/python-workers-examplescd 05-langchainuv run pywrangler dev
```

### Example code

Python

```
from workers import WorkerEntrypoint, Responsefrom langchain_core.prompts import PromptTemplatefrom 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())
```

```json
{"@context":"https://schema.org","@type":"TechArticle","@id":"https://developers.cloudflare.com/workers/languages/python/packages/langchain/#page","headline":"Langchain · Cloudflare Workers docs","description":"Use LangChain Python packages to build AI applications on Cloudflare Workers.","url":"https://developers.cloudflare.com/workers/languages/python/packages/langchain/","inLanguage":"en","image":"https://developers.cloudflare.com/dev-products-preview.png","dateModified":"2026-04-23","publisher":{"@type":"Organization","name":"Cloudflare","url":"https://www.cloudflare.com/"},"isPartOf":{"@type":"WebSite","@id":"https://developers.cloudflare.com/#website","name":"Cloudflare Docs","url":"https://developers.cloudflare.com/"}}
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/workers/","name":"Workers"}},{"@type":"ListItem","position":3,"item":{"@id":"/workers/languages/","name":"Languages"}},{"@type":"ListItem","position":4,"item":{"@id":"/workers/languages/python/","name":"Python Workers"}},{"@type":"ListItem","position":5,"item":{"@id":"/workers/languages/python/packages/","name":"Packages"}},{"@type":"ListItem","position":6,"item":{"@id":"/workers/languages/python/packages/langchain/","name":"Langchain"}}]}
```