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In Development Last updated: December 5, 2022
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FastAPI, a Python framework that allows you to develop web APIs, has been popular over the past few years.

API (Application Programming Interface) is the foundation of modern architecture. They allow applications to be modularized and decoupled. This allows you to create applications quickly and makes it easy to maintain them.

Therefore, it is a good idea to learn FastAPI if you plan to use Python to develop web applications. This article will teach you all about FastAPI basics.

What is FastAPI?

FastAPI is a Python-based web framework. It has attracted a lot of attention in recent years. Its development structure is similar to Flask, which was the most popular choice for those who wanted to learn Python web development.


FastAPI is simple to use, and its documentation is clear and easy to follow. FastAPI is used by tech giants such as Microsoft, Netflix, and Uber.

FastAPI has all the features you would expect from an API builder, but it’s not limited to these. You can use it to mount backward WSGI, which most users don’t know about.

FastAPI’s primary purpose is to build API endpoints, as the name suggests. This can be done as efficiently as returning Python dictionary data in JSON or using OpenAPI’s interactive Swagger UI.

FastAPI does not limit itself to APIs. It can be used for almost everything a web framework does, from delivering web pages with the Jinja2 template engine to serving WebSockets-powered applications.

Below are the advantages of FastAPI:

  • FastAPI allows you to validate the data type of the developer, even when using nested JSON queries.
  • It offers the autocomplete feature, which allows you to create applications in a shorter time and takes less effort.
  • It is compatible with the OpenAPI and JSON Schema vocabulary, which allows you to validate and annotate JSON documents.
  • FastAPI allows you to quickly build a GraphQL API using a Python library called graphene–python.
  • FastAPI is compatible with OAuth 2.0 as well as external providers.

Below are the disadvantages of FastAPI:

  • FastAPI is still a new framework, so there is little guideline community. It does not have enough external education information such as books, courses, or tutorials.
  • Because we must tie all the components together in FastAPI, the main file can become very large or crowded.

Unique Features of FastAPI

These are the unique features that make FastAPI the most popular Python web framework to date.

  • High Performance: FastAPI is more performant than other python frameworks. FastAPI’s speed-oriented framework makes it a top choice. Everything boils down to faster speed and better performance by leveraging Starlette features, creating APIs, and producing ready codes.
  • Fast to code: Developers don’t have to create anything new with production-ready codes. This speeds up the process by approximately 200% to 30%. FastAPI runs on Starlette and has many more features that can be used to build APIs for data validation and serialization. The framework already has all the necessary components in place, reducing the time it takes to code.
  • Minimal bugs: The framework has an auto-completion function that automatically inserts most of the code into the piece. This minimizes the possibility of errors and improves output quality.
  • Easy to understand: FastAPI doesn’t do anything except Modern Python. It is a modified version of Python 3.6 and contains no new syntax. The framework can be used by anyone who understands the language well.
  • Minimal effort: FastAPI generates OpenAPI documentation automatically with minimal effort from the developer. This information can be found under the application’s/doc directory. The documentation contains detailed information about API endpoints, return codes, response parameters, and other details.
  • Editor-support: All components of the framework are designed with autocompletion in mind. It’s simple, giving developers the ability to produce ready code. You can also test the code right from your browser with the interactive documentation.
  • Open standards: FastAPI’s Python web framework is a huge advantage. The framework is compatible with OpenAPI, formerly known as Swagger, which allows for creating APIs.

FastAPI Installation

Here are the simple steps to install FastAPI on Linux or Windows.

#1. FastAPI Installation on Linux

Install Python 3 on Linux using the command below:

sudo apt install python3
Install Python Linux

Install pip on Linux using the command below:

sudo apt install python3-pip
Install Python Pip Linux

Next, Install FastAPI on Linux.

pip install fastapi
Install FastAPI Linux

You will also need an ASGI server. So, install uvicorn using pip.

pip install "uvicorn[standard]"
Install uvicorn Linux

#2. FastAPI Installation on Windows

Install Python 3 on Windows using the Microsoft store. This will also install pip.

Install Python Windows

Next, install FastAPI on Windows.

pip install fastapi
Install FastAPI Windows

Finally, install ASGI server uvicorn.

pip install "uvicorn[standard]"
Install uvicorn Windows

New-age Uses of FastAPI

Here are some FastAPI new-age uses:

Automated Docs

Documentation about API types and endpoints is a must-have. This problem can be solved using OpenAPI, Swagger UI, and ReDoc. These are automatically packed with FastAPI. This allows you to concentrate on your code and not set up tools.

Typed Python

FastAPI uses Python 3.6 type declarations (thanks to Pydantic). This means it uses a Python feature that allows you to specify the type and type of a variable. This framework makes great use of it, giving you excellent editor support. Autocompletion works amazingly.


Pydantic already integrates validation into this framework. Validation of standard Python types and custom field validations can be done.

Security and Authentication

This is an important part of any API. We often just repeat the code, so why not incorporate some of it into our framework? FastAPI does exactly this.

The library supports HTTP Basic, OAuth2 tokens (JWT tokens), and header API keys.

Asynchronous nature

FastAPI, by default, supports asynchronous endpoints, making your code simpler and more efficient. This is a significant advantage over Flask. 

FastAPI vs. Flask: Key Differences

Usage differences

FastAPI, a full-stack platform that provides everything you need for building your API, is available. Flask, on the other hand, is a micro framework and doesn’t offer all the same features as FastAPI. Flask can be useful if you need to prototype an idea or create a simple web app quickly.

Flask and FastAPI are very different in the way they are used. The Flask framework can be used to prototype new ideas and applications, while the FastAPI framework can be used for building APIs. You can quickly build a backend server using it without any coding knowledge.

Small-scale websites and web applications

FastAPI is simple to use, lightweight and can be used for small-scale web and application development. It includes an object-relational layer (ORM), which handles data objects within the application, so you can quickly access them through coding.

The ORM layer keeps track of your databases and allows you to forget about manually updating them when new information is added, modified, or deleted from the website or application.


You may have noticed a basic difference: Flask uses WSGI for its standard interface, while FastAPI uses ASGI. As previously mentioned, WSGI processes requests synchronously. Requests are processed sequentially. One cannot start until the last task is completed.

ASGI handles requests asynchronously. This allows tasks to be completed at their own pace and does not require that they wait for others.


Another difference is the community. Flask is a community that has existed longer than FastAPI. This means great documentation and outside help from others who write about Flask.

FastAPI is still a new project, so the community has yet to grow quite as much. This means that although there is enough documentation, there isn’t much outside help.

Below is a summarised tables for FastAPI vs. Flask:

Data validation is built-in.It does not have data validation.
Asynchronous task support is availableAsynchronous task support is not available
Implements ASGI specificationsSupports WSGI applications
Automatic document supportManual document support
The error message is displayed in JSON formatThe error message is displayed on HTML pages
Smaller community supportRich community support

FastAPI or Flask: Which one should you choose?

FastAPI and Flask can quickly set up Python web servers and data science applications. Both require the same effort for deployment, but which framework is best for your next project?

FastAPI is the best option when speed and performance matter most. This framework is best if you are building a CDN and expecting significant traffic. FastAPI allows you to download the framework and immediately use it. The project template will save you time and help you save time.

FastAPI is a better option than Flask when you are building APIs. This is especially true when microservices and other considerations are considered. Flask is the best choice if you already have a lot of tools built around this framework.


So, that was all about FastAPI. FastAPI offers superior speed and performance. This framework is the best if you are building your content delivery network and expecting traffic. FastAPI’s innovative framework and project template will help you save time.

Flask could be better for creating APIs, particularly microservices. FastAPI is also better than Flask. Flask is a better choice if you already use it extensively.

You may also explore some popular Python Frameworks to build API.

  • Avi
    Avi is a tech enthusiast with expertise in trending technologies such as DevOps, Cloud Computing, Big Data and many more. He is passionate about learning cutting-edge technologies and sharing his knowledge with others through… read more
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