To deploy a FastAPI app on Heroku, you need three files: a Procfile that tells Heroku to run Uvicorn, a runtime.txt with your Python version, and a requirements.txt with fastapi, uvicorn, and gunicorn listed. Once those are in place, you create a Heroku app using the CLI and push your code via Git. That is the short version. The rest of this guide walks through the full setup including database connection, the errors that trip most developers up, what Heroku actually costs for a FastAPI project in 2026, and a faster path if you want to skip the configuration entirely. What You Need Before You Start Before deploying, make sure you have the following in place: A FastAPI app that runs locally without errors A requirements.txt file that includes fastapi, uvicorn, and gunicorn A Heroku account. The cheapest option is the Eco plan at $5 per month, but Eco dynos sleep after 30 minutes of inactivity.…