Does FastAPI still need Gunicorn?

For a long time Gunicorn+Uvicorn was the default setup for running FastAPI in production. However, I recently came across a blog post saying:

In the meantime, this combination of Gunicorn and Uvicorn is no longer needed, as Uvicorn now also handles worker management itself

I haven't found any other sources to verify this statement. Beside this, the official documentation only mention that the tiangolo/uvicorn-gunicorn-fastapi base Docker image is deprecated, but say nothing about Gunicorn+Uvicorn setup itself

So:

1. Does modern FastAPI need Gunicorn?
2. Is there any difference between fastapi run --workers 4 main.py and gunicorn main:app -w 4 -k uvicorn.workers.UvicornWorker now?

No. Since Uvicorn 0.30 (released May 2024), it's no longer necessary. That version introduced a built-in multi-process supervisor that supports:

• --workers to launch multiple processes

• Automatic restart of crashed workers

• Request limits via --limit-max-requests for leak mitigation

Shortly after, FastAPI’s creator deprecated the tiangolo/uvicorn-gunicorn-fastapi Docker image, stating:

Now that Uvicorn supports managing workers with --workers, including restarting dead ones, there's no need for Gunicorn.

Starting with FastAPI 0.110, the fastapi run CLI is just a thin wrapper around this new Uvicorn supervisor. So the official recommendation is now plain uvicorn or fastapi run for most use cases.