What Is FastAPI Used for?

What Is FastAPI Used for?

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In the context of web development, frameworks play a vital role when it comes to streamlining the creation of sophisticated and high-performing solutions. It is possible due to a structured foundation they ensure, seamlessly liquidating the complexity of coding tasks and accelerating the development process. One such valuable framework for web development is FastAPI, highlighted for its rapidity, simplicity, and versatility.

FastAPI, an innovative Python web framework, employs Python-type hints to ensure powerful data validation, as well as high reliability and enhanced clarity of the code. Moreover, its asynchronous capacity makes it exceptionally swift, delivering momentum response times for web applications. Due to the significance of robust performance and maintainability in web development, FastAPI is stated to be a great fit.

What is FastAPI used for? This article delves into this question, as well as its diversified application, exploring its use cases and determining why it stands out in the ecosystem of web frameworks. You should be aware of the strengths and usage of FastAPI to make relevant decisions on whether it aligns with your project requirements and contributes to the efficiency and success of your aspirations.

Understanding FastAPI

FastAPI is a modern, fast (as the name states) web framework for seamlessly designing APIs with Python 3.7+. Its key features comprise:

  • Automatic generation of OpenAPI and JSON Schema documentation
  • Built-in OAuth2 and API key security 
  • Dependency injection system
  • Interactive API exploration with Swagger UI
  • Automatic route handling
  • Asynchronous support using Python’s asyncio

FastAPI is created for streamlined usage, easier maintenance, and faster process execution, employing type hints for both input validation and automatic API documentation generation.

One feature worth highlighting is its high performance since FastAPI is based on Starlette and Pydantic. In brief, they are integral components that enhance the capabilities of FastAPI. Starlette serves as the asynchronous web framework that powers the underlying web functionality of FastAPI. Whereas Pydantic is a data validation library that is employed for data validation and parsing. This combination allows for rapid development and remaining top-notch performance.

Compared to other popular web frameworks like Flask and Django, FastAPI’s asynchronous capabilities can surpass them. It’s particularly valuable for applications requiring high concurrency. The automatic OpenAPI documentation is another advantage, simplifying it for developers to comprehend, test, and consume the APIs they create, thus optimizing the development process.

In essence, FastAPI combines the transparency of frameworks like Flask with the performance advantage of an asynchronous design. Its capacity to cater to a spectrum of development requirements establishes it as a forward-looking framework aiming to streamline and boost web API development in Python.

Key Components of FastAPI

FastAPI comprises critical components that contribute to its efficiency and functionality. Below, let’s define the elements that collectively enhance FastAPI’s reputation for being a high-performance and developer-friendly web framework for building APIs with Python.

Asynchronous programming with Python

Asynchronous programming with Python’s asyncio in FastAPI employs non-blocking I/O operations, allowing the server to handle numerous requests simultaneously without waiting in a queue for each to execute before dealing with the following. It is especially wise to use such a concurrency for solutions with heavy input-output operations, such as those incorporating network requests or database interactions and requiring excellent scalability.

FastAPI’s utilization of asyncio not only facilitates high efficiency but also enables the creation of responsive and scalable software. By allowing tasks to take over the governance within I/O-bound operations, FastAPI delivers optimal resource utilization, conditioning enhanced performance in scenarios where responsiveness and scalability are prioritized.

Automatic generation of OpenAPI and JSON Schema

The automatic generation of OpenAPI and JSON Schema documentation is a core feature, greatly simplifying the complex and time-consuming task of maintaining up-to-date API documentation. Through the engagement of Python-type hints, software engineers can annotate their code, providing a clear and expressive way to define the expected data types for API endpoints. This approach serves as a form of inline documentation, allowing to understand the structure of requests and responses directly from the code. In addition, and even more crucially, FastAPI leverages this type hint information to automatically generate comprehensive OpenAPI documentation, which, being a widely adopted standard, ensures compatibility with a broad spectrum of tools and services in the API ecosystem.

The backing of JSON Schema guarantees that the produced documentation aligns with this prevalent standard, defining JSON data structures. This not only boosts interoperability but empowers developers to validate JSON payloads against a standardized schema, ensuring consistency and reliability in handling API data. The automated creation of OpenAPI and JSON Schema documentation underscores FastAPI’s dedication to developer convenience, clarity, and seamless integration within the broader API ecosystem.

Fast Request Validation Using Pydantic

FastAPI integrates Pydantic as a robust data validation library, elevating the efficiency of request validation. Pydantic performs by enabling developers to determine data models and the places to apply these models to incoming requests, automatic validation, and parsing occur. As a result, the delivered data complies with the specified formats, enhancing the entire solidity and failure resistance of the API. 

Moreover, Pydantic contributes to streamlined error handling by providing clear feedback on deviations from expected formats, simplifying the debugging process for experts. Furthermore, the consistent application of data models promotes code consistency since developers adhere to predefined structures, resulting in a more maintainable and comprehensible codebase.

Use Cases of FastAPI

FastAPI use cases are pretty extensive. Being one of the best web frameworks according to TechEmpower, it introduces lots of benefits to each project it is used in. Let’s determine the best cases when to use FastAPI and obtain maximum value.

Building APIs

FastAPI is primarily designed to build robust and qualitative APIs, offering a modern alternative to traditional frameworks. Its use cases span various domains, from creating microservices to developing large-scale applications. Developers benefit from asynchronous support, Pydantic-powered data validation mentioned earlier, and automatic OpenAPI documentation. 

Compared to familiar frameworks like Flask, FastAPI’s performance, due to asynchronous programming, stands out, being advantageous for high concurrency and accelerated development. FastAPI’s support of type hints and automatic validation streamlines API creation, making it valuable for projects that put efficiency, scalability, and developer-friendly features first.

Microservices Development

Microservices are one of the popular solutions, that can be seamlessly developed by FastAPI. In a nutshell, it is a modular architectural approach where applications are organized into small, autonomous services. Leveraging asynchronous programming and automatic OpenAPI documentation, FastAPI simplifies the creation and maintenance of microservices. Its embedded support for handling concurrent requests efficiently aligns with the distributed essence of microservices. Tech teams benefit from the framework’s speed and intuitiveness, allowing for rapid development and scaling of microservices. FastAPI’s integration of Pydantic for data validation further enhances the reliability and consistency of communication between microservices, making it a go-to option for projects adopting a microservices architecture.

Real-time Applications

FastAPI is also well-suited for real-time applications and often used in such industries as eSports, Healthcare, Fleet Management, Hospitality, and FinTech, with its smooth support for WebSockets. With its use, developers can leverage FastAPI to build interactive and dynamic features in real-time, such as live-event updates, online booking, chat applications, live notifications, transactions, or collaborative editing platforms. The framework’s native support for asynchronous programming, combined with WebSockets capabilities, enables efficient handling of simultaneous connections, making it ideal for applications requiring instant communication. FastAPI’s seamless integration with WebSockets helps create responsive and interactive experiences, making it possible not only to implement traditional REST APIs but also to cover dynamic, real-time functionalities in various web applications.

Machine Learning and Data Science

Seamless integration with powerful Machine Learning libraries is another peculiarity of FastAPI, enabling the development of data-driven applications. It’s an excellent fit for asynchronous programming and seamlessly fits in the initial concurrency concept of many Machine Learning tasks, even more refining FastAPI’s ability to build robust and data-driven applications. Technicians can efficiently deploy machine learning models as APIs using FastAPI, facilitating simple integration with frontend applications or other necessary services. With FastAPI’s automatic OpenAPI documentation and data validation through Pydantic, the framework ensures clarity and reliability in the API development process.

Advantages of Using FastAPI

Let’s now move on and discuss what are the core values of FastAPI.


FastAPI possesses significant advantages due to the asynchronous capabilities leveraging Python’s asyncio, as mentioned earlier. This delivers FastAPI with the capacity to handle numerous concurrent requests efficiently. Benchmark comparisons truly showcase FastAPI’s power in response times to traditional frameworks like Flask and Django. 

Average time for the first call after the server starts up according to research data posted on Dev.to:

FrameworkResponse times
FastAPI17 ms
Django517.2 ms
Flask507. 2 ms
Average time for the first call after the server starts up

High performance is crucial for project cases dealing with real-time data and requiring low-latency communication, such as chat applications or streaming services. The asynchronous design allows FastAPI to handle numerous simultaneous connections without unnecessary resource overhead, making it an ideal choice for projects prioritizing speed, scalability, and responsiveness. Consequently, the performance advantages of FastAPI vs Flask and Django highlight it as a solid option for projects seeking high-performing web frameworks.

Automatic Documentation

FastAPI offers automatic OpenAPI documentation generation, seamlessly integrating with Swagger UI for interactive documentation. This feature streamlines the process of documenting APIs by dynamically creating comprehensive documentation based on the provided models and route definitions. OpenAPI compatibility enhances interoperability, allowing developers to explore and understand endpoints. The Swagger UI integration adds a user-friendly layer, enabling interactive exploration of endpoints directly from the documentation. This not only promotes clarity in API usage but also simplifies testing during development. FastAPI’s commitment to automatic documentation significantly reduces the manual effort typically associated with keeping API documentation up-to-date.

FastAPI’s automatic documentation capabilities align with modern development practices, reducing the complexity and overload on developers to maintain separate documentation. This way, the feature saves a lot of time while, in parallel, significantly mitigates the risk of documentation becoming outdated. As a result, the automatic documentation capability provides enhanced efficiency, accuracy, and collaboration in the API development process. Needless to say, you should hire FastAPI developers with extensive experience and a proven track record of this framework’s engagement to make maximum use of its capacity.

Type Checking and Validation

Pydantic significantly elevates type checking and validation in FastAPI by providing a declarative way to define data models. Leveraging Python’s type hints, Pydantic allows developers to specify the expected data structure, both for incoming requests and outgoing responses. The output ensures automatic validation, guaranteeing that the received data aligns with the selected types. Pydantic’s integration with FastAPI also performs data validation, ensuring that incoming requests align with the specified models, thus maintaining data integrity.

When handling incoming requests, FastAPI automatically validates the data against the Pydantic models, pointing out the appropriate errors in case the data doesn’t match the expected structure. This not only improves the reliability of APIs but also simplifies error handling for developers.

Similarly, in responses, FastAPI employs the Pydantic models to validate that the data being returned conforms to the necessary structure. This guarantees consistency between the API’s documentation and its actual behavior.

As a result, Pydantic’s combination of type hints and declarative data model definitions enhances the clarity and correctness of code in FastAPI. The automatic type checking and validation contribute to the overall robustness and reliability of data handling in FastAPI applications.


FastAPI is truly a cutting-edge web framework for API development, offering outstanding key features that highlight it in the Python ecosystem. The capacities and opportunities like automatic generation of OpenAPI documentation, seamless integration with asynchronous programming, and robust data validation through Pydantic accelerate the development of high-performance APIs. Its advantages exceeding traditional frameworks, such as Flask, may be demonstrated through response time tests, as well as scenarios requiring scalability and rapid development.

To developers seeking high-performance frameworks, we encourage considering the FastAPI usage for your following projects. Make use of its intuitive syntax, automatic validation, and asynchronous capabilities to streamline the development process. In case you aspire to build modern, data-driven applications, the framework’s adherence to clarity, speed, and reliability positions it as a powerful tool in the hands of developers.

Considering everything, FastAPI offers a vital advancement in web framework technology, aligning with the demands of the current and dynamic software development sector. Experience the full capacity of FastAPI in API development by incorporating it into your following projects, and bring in the maximum benefits it delivers to speed, documentation, and overall software efficiency. Increase the quality and user satisfaction of your product with FastAPI, making API development flow elevated, smooth, and reliable.

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