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Top 23 Flask Interview Questions and Answers

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Flask is an open-source web framework written in Python that is designed to be lightweight, modular, and easy to use.It is a popular choice for creating web applications and APIs.As such, Flask is a great language for developing web applications.

If you are looking for a job in web development, it would be beneficial to have a solid understanding of Flask. To help you prepare for your next job interview, we have compiled a list of the most common Flask interview questions and answers. We’ve included some general tips on how to answer these questions, as well as a few examples of answers that you could give.

job interview

This blog post will provide you with the best tips and advice to help you ace your interview and land the job of your dreams.We’ll start by discussing the basics of Flask and then move on to cover the most common questions.We’ve also included some sample questions and answers that you can use to practice and prepare for the interview.

By the end of this blog post, you’ll be well-prepared for your next job interview and have the confidence to answer any Flask-related questions that may come your way. So read on and get ready to impress your interviewer with your knowledge and expertise.

Overview of Flask Interview Process

The Flask interview process generally begins with a phone interview. During this stage, the interviewer will ask questions about your background and experience with Flask, as well as any other relevant topics. From there, an in- person interview may follow, which will typically include more detailed questions about your technical skills and experience.

The second stage of the Flask interview process usually consists of a technical interview. Here, the interviewer will ask questions related to the specifics of Flask and its components. These can include questions about web frameworks, templates, forms, security, and data storage. The interviewer may also ask questions about specific coding challenges that they have prepared in order to assess your technical abilities.

The third stage of the Flask interview process is the final interview. Here, the interviewer will likely ask questions about your design and development philosophy. They may also ask questions about your experience working with clients and other stakeholders, as well as your ability to adapt to new environments and technologies. At this stage, the interviewer may also ask you to provide examples of projects you have completed in the past, and to discuss any challenges you encountered or solutions you developed.

Overall, the Flask interview process is designed to assess your technical skills and ability to use the framework. By preparing for this process and familiarizing yourself with the topics discussed during the interviews, you can increase your chances of success.


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Top 23 Flask Interview Questions and Answers

1. What is Flask?

Flask is a Python microframework used to create web applications. It was created to make web development easier and faster. Flask provides a relatively simple and easy-to-learn interface for creating web applications that use the Python language. It is a lightweight framework, meaning it does not come with many of the tools and libraries that are commonly used in web development, allowing developers to customize their applications. Flask also supports extensions, which allow developers to extend the functionality of their applications and create more powerful web applications.

2. What are some of the advantages of using Flask?

Flask has a few advantages over other frameworks, such as Django or Ruby on Rails. Firstly, Flask is lightweight and does not come with the extra features that many other frameworks come with, meaning it’s easier for developers to customize the framework and make applications according to their own needs. Flask is also very fast and efficient, making it ideal for quick development. Finally, Flask is well-documented and has a great community support system, making it easy to find support for any issues that may arise.

3. What is the Jinja2 template engine?

Jinja2 is a template engine written in Python used to generate HTML or other markup formats. It’s often used in conjunction with the Flask framework, as it allows developers to create dynamic web applications with HTML templates. Jinja2 has a few advantages over other template engines, such as being fast and lightweight, as well as being easily extensible. Additionally, Jinja2 can be used to create custom filters, macros, and other custom elements that make web development easier.

4. What is the difference between a “view” and a “template” in Flask?

A view is a function that is used to render a template. A template is an HTML file that contains the data to be rendered. A view is responsible for taking the data from the template and rendering it in the proper format. A view is also responsible for handling user requests, such as getting data from a form or database and then sending it back to the user.

5. What is the structure of a Flask application?

A Flask application is typically structured in the following way: the file contains the main logic and the configuration of the application; the file contains the database models used in the application; the file contains the views used to render the templates; the templates/ directory contains all the HTML templates used in the application; the static/ directory contains all the static files like images, stylesheets, and JavaScript files. Additionally, the file contains the application configuration; the requirements.txt file contains the list of dependencies; and the tests/ directory contains the unit tests for the application.

6. What is the role of the Flask object in a Flask application?

The Flask object is the main application object used in a Flask application. It is responsible for handling requests, instantiating views, and providing access to the configuration and other variables. The Flask object can be imported and used to create an application instance which is used to configure and run the application.

7. What is the Flask-WTF extension?

The Flask-WTF extension is a Flask extension that integrates the WTForms Python library with the Flask framework. WTForms is a library used to create web forms and validate user input. Flask-WTF allows developers to easily create forms and validate user input with minimal code.

8. What is the difference between a session and a cookie in a Flask application?

A session is data that is stored on the server and associated with a particular user and can be used to store user-specific data. A cookie is a small piece of data that is stored on the user’s computer and can be used to store information about the user’s preferences or authentication state.

9. How does Flask handle form submission?

When a form is submitted, Flask will use the request.form object to access the data from the form. The data is then processed by the view function, which is responsible for handling the data and providing it to the template. The template will then display the processed data.

10. What is the role of the “” method in a Flask application?

The app. run() method is used to start a Flask application. It is responsible for setting up the application, loading the configuration and instantiating the view functions. Once the application is running, it will start listening for incoming requests and will respond accordingly.

11. What is Flask and what makes it so popular?

Flask is a lightweight web application framework written in Python. It is designed to make web development quick and easy. Flask is simple to use, yet powerful enough to support enterprise level applications. Flask makes it easy to define routes, create views, and handle requests. It is also well-documented, making it easy to get started with. Flask’s modularity and scalability make it a great choice for developing both small and large applications. Its popularity comes from its ease of use, flexibility in building applications, and its large community of developers who help each other out.

12. What is the Jinja2 Templating Language?

Jinja2 is a templating language used with the Flask web framework. It allows developers to create custom HTML templates and dynamically generate webpages from data. It is a powerful and secure language that makes it easy to separate code from design, allowing developers to focus on the logic and structure of their applications, rather than the look and feel. Jinja2 supports inheritance and includes powerful features for manipulating strings, arrays, and dictionaries.

13. What are Flask Blueprints?

Flask blueprints are components of a Flask application that define and contain routes, views, and other functionality. Blueprints can be used to organize larger Flask applications into smaller, more manageable parts. They also allow developers to create and use components that can be used across multiple applications. Blueprints provide a way to structure and organize an application in a modular way, which makes it easier to maintain and extend.

14. What are the differences between a view and a route in Flask?

A view in Flask is an endpoint that handles the rendering of HTML templates. A view is a Python function that takes in a request and returns a response. A route, on the other hand, is a mapping between a URL path and a view. Routes contain the logic for determining which view to render and how to handle the request.

15. How does Flask handle requests?

Flask uses the Werkzeug WSGI toolkit to handle requests. The WSGI toolkit provides the interface between Flask and the web servers. When a request comes in, the web server forwards it to the WSGI toolkit. The Werkzeug toolkit then parses the request and sends it to the Flask application. The Flask application then generates a response and returns it to the WSGI toolkit, which passes it back to the web server.

16. How do you use sessions in Flask?

In Flask, sessions are handled with the Flask-Session package. This package provides the necessary tools to manage sessions in a Flask application. With Flask-Session, users can store data in the session object that is accessible during the lifetime of the user. This can be used to keep track of user preferences, authentication information, or any other data necessary for the application.

17. How do you set up a database in Flask?

In Flask, databases can be set up using the Flask-SQLAlchemy extension. This extension provides an ORM (Object Relational Mapper) that allows developers to interact with databases in a Pythonic way. To use Flask-SQLAlchemy, developers need to define a base model and create tables for their models. Then, queries can be created and executed to access, update, and delete the data in the database.

18. What is the purpose of a decorator in Flask?

Decorators in Flask are used to add functionality to existing functions. Decorators wrap an existing function and add extra functionality to it. This can be used to add authentication or authorization to a view, or to add additional functionality without changing the existing code. Decorators are a useful feature of Flask as they allow developers to easily extend the functionality of an application without having to rewrite existing code.

19. What are the advantages of using Flask?

Flask is a lightweight web framework that is designed to be quick and easy to use. It makes it easy to define routes, create views, and handle requests. Its modularity and scalability make it a great choice for developing both small and large applications. It is well-documented, making it easy to get started with. Flask’s large community of developers help each other out, making it easy to find answers to questions. Additionally, it has great security features such as password hashing and session management.

20. What are some of the disadvantages of using Flask?

One of the main disadvantages of using Flask is that it is not as feature-rich as some other web frameworks, such as Django. Flask does not come with a built-in user authentication system, so developers must implement their own. Additionally, Flask does not have an Object Relational Mapper (ORM) built in, and so developers must use an extension such as Flask-SQLAlchemy if they want to use a database.

21. What is the Flask-WTF extension?

The Flask-WTF extension is a package that makes it easy to create forms in Flask. It provides tools to generate HTML forms, validate form data, and process form submissions. It also allows developers to add custom validation and error messages to their forms. This makes it easier to create forms with complex validations without having to write a lot of code.

22. How do you use templates in Flask?

Flask uses the Jinja2 templating language to render HTML templates. The templates are stored in the templates directory of your application. To use a template, developers create an HTML template in the templates folder and then render it in the view. The view passes variables to the template, which can be used to display dynamic data.

23. How do you set up error handling in Flask?

Error handling in Flask is done using the Flask. error handler decorator. This decorator allows developers to define custom error handling functions that get called when an exception occurs. The error handler function can be used to return a custom response, log an error, or even send an email. This allows for custom error handling for each application, making it easier to debug and maintain.

Tips on Preparing for a Flask Interview

  1. Brush up on the basics of Python and Flask: Knowing the basics of Python and Flask is essential for any Flask interview. Make sure you know how to write and debug basic Python code, use the Flask framework, and understand Flask best practices.
  2. Have examples of Flask projects ready: Be prepared to talk about any Flask projects you have done in the past. Have the code and other related artifacts handy to walk the interviewer through your project.
  3. Learn the Flask session and authentication methods: Become familiar with the different ways Flask can manage sessions and authentication. Know the benefits and drawbacks of each so you can discuss them with the interviewer.
  4. Read up on Flask security: Learn the different security measures you can use in Flask, such as securing cookies and encrypting data.
  5. Practice answering typical questions: Read up on common Flask interview questions and practice answering them.
  6. Think of questions to ask the interviewer: Prepare a few questions to ask the interviewer about the role, the company, and their approach to Flask development.
  7. Research the company: Research the company where you are interviewing and understand the products and technologies they use.
  8. Prepare for technical tests: Some companies give technical tests as part of the interview process. Make sure you’re ready for them by studying the relevant technologies.
  9. Be prepared to talk about your experience: Be prepared to discuss your experience with Flask development. Have specific examples and stories to share that demonstrate your skills and knowledge.
  10. Dress appropriately: Make sure you dress appropriately for the interview.
  11. Plan your journey: Make sure you know exactly how to get to the interview venue and plan to arrive a few minutes early.
  12. Learn about the team: Do some research and try to learn about the people who will be interviewing you.
  13. Have the right tools ready: Have a


The Flask web framework is a powerful tool for building web applications. With its lightweight, easy- to- use design and its ability to integrate with other frameworks, it has become a popular choice for developers. Knowing the right set of Flask interview questions and answers can help you land your next job. From common questions to more technical questions, this guide has all the answers you need to ace your next Flask interview. With the right knowledge and practice, you will be ready to confidently demonstrate your skills and prove that you are the right fit for the job.