Some notable AI Gateway are: For this guide, we’ll use Portkey as our AI Gateway.

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Setup Portkey

You can setup Portkey locally, or use the hosted version at portkey.ai. Once you have Portkey setup, continue with the following steps.

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Add Portkey to your project

npm install portkey

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Using Portkey to call OpenAI models

const handler: Chat = async ({ userMessage }) => {
  const { userMessage } = content;
  // Create Portkey client
  const portkey = new Portkey({
    Authorization: "Bearer sk-xxxxx",
    provider: "openai",
  });
  // Call the API
  const response = await portkey.chat.completions.create({
    messages: [{ role: "user", content: userMessage }],
    model: "gpt-3.5-turbo",
  });
  return {
    message: response.choices[0].message.content,
  };
};

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Using Portkey to call any LLM model with App Config

To be able to easily swap different LLM models in your application, you can use App Config along with Portkey. This will allow you to use any LLM model without changing your code and just updating the AppConfig. 
import { Portkey } from "portkey";

interface AppConfig {
  model: string;
  provider: string;
}

const handler: Chat = async ({ userMessage, appConfig }) => {
  const { model, provider } = appConfig;
  // highlight-start
  const portkey = new Portkey({
    Authorization: "Bearer sk-xxxxx",
    provider: provider,
    // ...additional authorization params
  });
  const response = await portkey.chat.completions.create({
    messages: [{ role: "user", content: userMessage }],
    model: model,
  });
  // highlight-end
  return {
    message: response.choices[0].message.content,
  };
};
Using AppConfig to swap LLM models allows you to easily run experiments with different variations of your applications locally, or run A/B tests in production without changing your code.