How to Build and Deploy a Node.js App That Uses OpenAI’s APIs Near the end of 2023, ChatGPT announced that it had 100M weekly users. That’s a massive base of users who want to take advantage of the convenience and power of intelligent question answering with natural language. With this level of popularity for ChatGPT, it’s no wonder that software developers are joining the ChatGPT app gold rush, building tools on top of OpenAI’s APIs. Building and deploying a GenAI-based app is quite easy to do—and we’re going to show you how! In this post, we walk through how to build a Node.js application that works with OpenAI’s Chat Completions API and uses its function calling feature. We deploy it all to Heroku for quick, secure, and simple hosting. And we’ll have some fun along the way. This project is part of our new Heroku Reference Applications , a GitHub organization where we host different projects showcasing architectures to deploy to Heroku . Ready? Let’s go!…