# Zero\-configuration FastAPI backends

**Published:** September 25, 2025 | **Authors:** Ricardo Gonzalez

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[FastAPI](https://fastapi.tiangolo.com/), a modern, high-performance, web framework for building APIs with [Python](https://vercel.com/docs/functions/runtimes/python), is now supported with zero-configuration.

**app.py**
```python
from fastapi import FastAPI 
app = FastAPI() 
@app.get("/") 
def read_root(): 
    return {"Hello": "World"}
```

Vercel's [framework-defined infrastructure](https://vercel.com/blog/framework-defined-infrastructure) now recognizes and deeply understands FastAPI applications. This update removes the need for redirects in `vercel.json` or using the `/api` folder.

Backends on Vercel use [Fluid compute](https://vercel.com/fluid) with [Active CPU pricing](https://vercel.com/blog/introducing-active-cpu-pricing-for-fluid-compute) by default. This means your FastAPI app will automatically scale up and down based on traffic, and you only pay for what you use.

[Deploy FastAPI on Vercel](https://vercel.com/templates/python/fastapi-python-boilerplate) or visit the [FastAPI on Vercel documentation](https://vercel.com/docs/frameworks/backend/fastapi).

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📚 **More updates:** [View all changelog entries](/changelog/sitemap.md) | [Blog](/blog/sitemap.md)