LiteLLM

LiteLLM is an open-source library that provides a unified interface to call LLMs. This guide demonstrates how to integrate Vercel AI Gateway with LiteLLM to access various AI models and providers.

1. Create a new project

   First, create a new directory for your project:

   terminal

   mkdir litellm-ai-gateway
   cd litellm-ai-gateway

2. Install dependencies

   Install the required LiteLLM Python package:

   terminal

   pip install litellm python-dotenv

3. Configure environment variables

   Create a .env file with your Vercel AI Gateway API key:

   .env

   VERCEL_AI_GATEWAY_API_KEY=your-api-key-here

   If you're using the AI Gateway from within a Vercel deployment, you can also use the VERCEL_OIDC_TOKEN environment variable which will be automatically provided.

4. Create your LiteLLM application

   Create a new file called main.py with the following code:

   main.py

   import os
   import litellm
   from dotenv import load_dotenv
    
   load_dotenv()
    
   os.environ["VERCEL_AI_GATEWAY_API_KEY"] = os.getenv("VERCEL_AI_GATEWAY_API_KEY")
    
   # Define messages
   messages = [
       {"role": "system", "content": "You are a helpful assistant."},
       {"role": "user", "content": "Tell me about the food scene in San Francisco."}
   ]
    
   response = litellm.completion(
       model="vercel_ai_gateway/openai/gpt-5.4",
       messages=messages
   )
    
   print(response.choices[0].message.content)

   The following code:

   • Uses LiteLLM's completion function to make requests through Vercel AI Gateway
   • Specifies the model using the vercel_ai_gateway/ prefix
   • Makes a chat completion request and prints the response

5. Running the application

   Run your Python application:

   terminal

   python main.py

   You should see a response from the AI model in your console.