FastAPI Python Development Framework

FastAPI Python Framework

FastAPI is a cutting-edge, high-performance web framework for building APIs with Python 3.6+ types, based on standard Python type hints. Its primary objective is to allow the quick creation of code while ensuring robust and optimal performance. With automatic interactive API documentation built-in, the framework has gained immense popularity since its inception.

Intro to FastAPI

FastAPI, developed by Sebastián Ramírez and first released in December 2018, is an innovative web framework for building APIs using Python 3.6+ types. Harnessing the power of Python’s type hints, FastAPI automatically handles data validation, serialization, and documentation generation, resulting in rapid, type-safe development practices. Its asynchronous capabilities, inspired by modern asynchronous frameworks, offer optimized performance for I/O-bound tasks, making FastAPI not only a developer-friendly choice but also a performance-efficient one in the competitive landscape of web frameworks.

FastAPI Quick Facts

  1. Type Annotations: FastAPI leverages Python 3.6+ type hints to automatically validate request data, generate API documentation, and provide editor support, enhancing development speed and reducing errors.
  2. Performance: FastAPI is notably one of the fastest Python web frameworks for API development, comparable in performance to Node.js and Go, especially when handling large numbers of requests.
  3. Automatic API Docs: The framework automatically generates interactive API documentation (using Swagger UI and ReDoc) from the code, streamlining API testing and collaboration.
  4. Asynchronous Support: Built-in support for asynchronous request handling makes FastAPI highly efficient for I/O bound operations, enabling it to manage high concurrency gracefully.
  5. Integrated Security: FastAPI has built-in OAuth2 and JWT implementations, simplifying the process of adding secure authentication and authorization to applications.

Core Features of FastAPI

  • Type Hints: One of FastAPI’s hallmarks is its utilization of Python’s type hints. This makes the code easy to understand, reduces the chances of bugs, and allows automatic data validation.
  • Data Serialization: It has integrated support for data validation and data serialization using Pydantic.
  • Automatic API Documentation: FastAPI automatically generates interactive API documentation for your application using tools like Swagger UI and ReDoc.
  • OAuth and JWT: It offers an easy and secure way to implement OAuth2 with Password (and hashing) using JWT tokens.
  • Asynchronous Capabilities: Asynchronous request handling enables handling a large number of concurrent requests, ideal for I/O bound operations and high concurrency scenarios.

Advantages of Using FastAPI

  • Performance: FastAPI is one of the fastest frameworks for building APIs, only slower than Node.js and Go when it comes to data handling.
  • Rapid Development: The automatic interactive API documentation and type hints significantly speed up the development process.
  • Type Safety: The use of Python type hints ensures type safety, reducing the chances of runtime errors.
  • Extensibility: It integrates seamlessly with other Starlette libraries and components.

Common FastAPI Use Cases

  • RESTful APIs: Its primary strength lies in developing modern, performant, and robust APIs.
  • Microservices: Thanks to its asynchronous capabilities, it is apt for building microservice architectures.
  • Data-Driven Applications: Easily handle and validate complex data structures using Pydantic.

Alternatives to FastAPI

Comparing FastAPI to alternative frameworks is a good way to evaluate its strengths and weaknesses. The chart below is a comparison of the FastAPI with the closest alternatives, including Flask, Django, and Express.js.

Getting Started with FastAPI


  • Python 3.6+
  • Knowledge of Python’s type hints


Install FastAPI using pip:

pip install fastapi

Install an ASGI server, such as Uvicorn:

pip install uvicorn

Your First FastAPI Application

Create a file named and write the following code:

from fastapi import FastAPI

app = FastAPI()

def read_root():
    return {"Hello": "World"}

Running the Application

Run your FastAPI application using Uvicorn:

uvicorn main:app --reload

Visit in your browser. You should see the response {"Hello": "World"}.

Interactive API Docs

Navigate to This automatically generated interactive documentation lets you test your API directly from the browser.

Doing More with FastAPI

  • Implement path and query parameters, request bodies, and headers.
  • Explore FastAPI’s dependency injection system.
  • Dive deeper into Pydantic models and data validation.

FastAPI offers an optimal mix of rapid development, robustness, and high performance. With its focus on modern Python features, especially type hints, it ensures code clarity and reduces the chances of errors. Whether you’re a seasoned web developer or just starting with API development, FastAPI promises a seamless and efficient experience, making it a top choice in today’s web development landscape.

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