What is FastAPI?

As the name suggests, FastAPI is a modern Python framework designed for building RESTful APIs with high performance and minimal boilerplate. In 2026, it has become the industry standard because it’s exceptionally fast, reliable, and includes powerful out of the box features — such as automatic interactive documentation and native support for asynchronous programming.

How to install?

These commands install FastAPI along with Uvicorn, a lightning-fast server used to run your application. You can use uv, fast and reliable package manager for Python, written in Rust:

uv add fastapi[standard]

or use the default pip manager with:

pip install fastapi[standard]

How to use?

After we have installed the FastAPI package, we can open our favorite code editor (VS Code for example) and create an empty project. In a file called main.py we can write the following:

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def read_root():
    return {"message": "Hello, World!"}

If we run the following command in the terminal to start our app, we should see an output like this:

fastapi dev

If everything worked so far, upon going to http://localhost:8000/ we should see this or something similar depending on the browser:

What more?

FastAPI directly integrates OpenAPI, which means your documentation is always in sync with your code. By visiting http://localhost:8000/docs, you get an interactive Swagger UI where you can test your endpoints in real-time without needing external tools like Postman. For a more formal layout, you can also access http://localhost:8000/redoc, giving you professional-grade API documentation the second you hit "save."

Why Start with FastAPI?

As we’ve seen in our look at FastAPI Quickstart in 2026, this framework is more than just a speed-demon — it’s a developer-friendly ecosystem that does the heavy lifting for you. Whether you are drawn to it for the automatic interactive documentation or its native support for asynchronous programming, FastAPI ensures that your transition from a “Hello World” to a high-performance, production-ready API is as smooth as possible.