Creating APIs, or application programming interfaces, is an important part of making your software accessible to a broad range of users. In this tutorial, you will learn the main concepts of FastAPI and how to use it to quickly create web APIs that implement best practices by default.

By the end of it, you will be able to start creating production-ready web APIs, and you will have the understanding needed to go deeper and learn more for your specific use cases.

In this tutorial, you’ll learn how to:

Use path parameters to get a unique URL path per item Receive JSON data in your requests using pydantic Use API best practices, including validation, serialization, and documentation Continue learning about FastAPI for your use cases

What Is FastAPI?

FastAPI is a modern, high-performance web framework for building APIs with Python based on standard type hints. It has the following key features:

• Fast to run: It offers very high performance, on par with NodeJS and Go, thanks to Starlette and pydantic.
• Fast to code: It allows for significant increases in development speed.
• Reduced number of bugs: It reduces the possibility for human-induced errors.
• Intuitive: It offers great editor support, with completion everywhere and less time debugging.
• Straightforward: It’s designed to be uncomplicated to use and learn, so you can spend less time reading documentation.
• Short: It minimizes code duplication.
• Robust: It provides production-ready code with automatic interactive documentation.
• Standards-based: It’s based on the open standards for APIs, OpenAPI and JSON Schema

The framework is designed to optimize your developer experience so that you can write simple code to build production-ready APIs with best practices by default.

Install FastAPI

As with any other Python project, it would be best to start by creating a virtual environment. If you are not familiar with how to do that, then you can check out the Primer on Virtual Environments.

The first step is to install FastAPI and Uvicorn using pip:

python -m pip install fastapi uvicorn[standard]

With that, you have FastAPI and Uvicorn installed and are ready to learn how to use them. FastAPI is the framework you’ll use to build your API, and Uvicorn is the server that will use the API you build to serve requests.

First Steps

To get started, in this section, you will create a minimal FastAPI app, run it with a server using Uvicorn, and then learn all the interacting parts. This will give you a very quick overview of how everything works.

Create a First API

A basic FastAPI file looks like this:

Use path parameters to get a unique URL path per item Receive JSON data in your requests using pydantic Use API best practices like validation, serialization, and documentation Continue learning about FastAPI and pydantic for different use cases You’re now ready to start creating your own highly performant APIs for your projects. If you want to dive deeper into the world of FastAPI, then you can follow the official User Guide in the FastAPI documentation.