Question 1

How do I host a Python web app on Phemeral?

Accepted Answer

Simply connect your Github repo to a Phemeral project and make a push. Phemeral analyzes your source to determine the correct configuration, and then builds and deploys your app automatically. Your app is then accessible from either an assigned URL or from one of your custom domains.

Question 2

Do I need a Dockerfile or a config file?

Accepted Answer

Nope. Detection runs off your source, so there is no container configuration and no YAML to maintain. If your web app needs a specific start command, you can set a custom start command in your project's Settings tab.

Question 3

How do I host a Django app?

Accepted Answer

When hosting a Django app on Phemeral, your app's structure is automatically detected. Phemeral will find where your Django app's ASGI application is, and then build and deploy your app. Your app will be run with uvicorn using your app's ASGI interface, or you can set your own start command if you'd like.

Question 4

How do I host a Flask app?

Accepted Answer

When hosting a Flask app on Phemeral, your app's structure is automatically detected. Flask is WSGI and started with gunicorn. Your app will be run with gunicorn using the app's WSGI interface, or you can set your own start command if you'd like.

Question 5

How do I host a FastAPI app?

Accepted Answer

When hosting a FastAPI app on Phemeral, your app's structure is automatically detected. FastAPI is ASGI and started with uvicorn. Your app will be run with uvicorn using the app's ASGI interface, or you can set your own start command if you'd like.

Question 6

What makes Phemeral good for Python hosting specifically?

Accepted Answer

Phemeral is built specifically for Python web applications, so detection, builds and the runtime are tuned for them. You get the benefits of serverless hosting, without needing to deal with the traditional complexity of setting up a web app on Lambdas or other serverless providers.

Question 7

What about databases?

Accepted Answer

Phemeral provides fully managed serverless Postgres. So your app is hosted on serverless compute, and the database is as well, giving you an end to end serverless developer experience. Never think about a scaling policy again.

Question 8

Which frameworks are supported?

Accepted Answer

Any Python web application can be hosted. Some are automatically detected, and for others, you'll need to set a custom start command. FastAPI, Flask and Django are autodetected. Litestar, Starlette, Sanic, FastHTML, and all other frameworks are supported with a custom start command. Theoretically, you could host a raw ASGI or WSGI app if you wanted.

Question 9

Which versions of Python are supported?

Accepted Answer

Python 3 and above.

Question 10

Which package managers work?

Accepted Answer

uv, poetry, and pip. Basically, as long as you have a requirements.txt or pyproject.toml somewhere in your project, Phemeral can figure out and install your dependencies, regardless of the package manager you're using.

Question 11

What does serverless mean on Phemeral?

Accepted Answer

Your application's compute automatically scales up on demand, scales to zero when idle, and you're only billed for what it actually uses instead of provisioned capacity. You don't need to write or maintain scaling policies.

Question 12

Are there cold starts?

Accepted Answer

Not really. The only "cold start" you might notice will be less than 50ms. So basically, there aren't "real" cold starts

Question 13

Do WebSockets and SSE work?

Accepted Answer

Yup!

Question 14

Do I need an adapter like Mangum?

Accepted Answer

No. Your app runs like it does on your machine (pretty much), just on serverless infrastructure. No handler and no adapter.

Question 15

How does scale-to-zero work?

Accepted Answer

When your app isn't receiving any traffic, Phemeral will automatically, scale your compute down to zero, so you're not charged for idle apps.

Question 16

Do I need to configure scaling policies?

Accepted Answer

Nope. Compute is allocated as your traffic changes and you're only billed for what you use.

Question 17

How do serverless databases work?

Accepted Answer

The cluster's compute automatically scales between 0.25 and 8 vCPU with 1 GB to 32 GB of RAM. After five minutes without traffic a cluster scales to zero and the next query wakes it within a few hundred milliseconds.

Question 18

How should my app handle connections?

Accepted Answer

Every cluster is fronted by a connection pooler that supports up to 10,000 concurrent connections. A direct URI is available when you need to bypass the pooler.

Question 19

What does it cost to get started?

Accepted Answer

It's free to get started! Once your projects are receiving substantial traffic and you want to put things into production, you can upgrade to the Pro plan.

Question 20

What does Pro add?

Accepted Answer

Unlimited team members, a $20/month compute credit against usage-based charges, no hard pausing when you exceed the credit, 100-day build cache retention instead of 10 days, and access to managed Postgres.

Question 21

How is usage measured?

Accepted Answer

Across four dimensions: requests, compute as RAM GB-hours, outbound data transfer in GB, and build minutes. Managed Postgres is metered separately per cluster on compute GB-hours, storage GB-hours and egress.

Questions about hosting Python on Phemeral.

Getting started

Frameworks & Python versions

Serverless & cold starts

Scaling

Databases

Pricing & billing

Ship Python.
Not infrastructure.

Questions about hosting Python on Phemeral.

Getting started

How do I host a Python web app on Phemeral?+−

Do I need a Dockerfile or a config file?+−

How do I host a Django app?+−

How do I host a Flask app?+−

How do I host a FastAPI app?+−

What makes Phemeral good for Python hosting specifically?+−

What about databases?+−

Frameworks & Python versions

Which frameworks are supported?+−

Which versions of Python are supported?+−

Which package managers work?+−

Serverless & cold starts

What does serverless mean on Phemeral?+−

Are there cold starts?+−

Do WebSockets and SSE work?+−

Do I need an adapter like Mangum?+−

Scaling

How does scale-to-zero work?+−

Do I need to configure scaling policies?+−

Databases

How do serverless databases work?+−

How should my app handle connections?+−

Pricing & billing

What does it cost to get started?+−

What does Pro add?+−

How is usage measured?+−

Ship Python.Not infrastructure.

Ship Python.
Not infrastructure.