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Flask vs Javalin: What are the differences?

What is Flask? a microframework for Python based on Werkzeug, Jinja 2 and good intentions. Flask is intended for getting started very quickly and was developed with best intentions in mind.

What is Javalin? Simple REST APIs for Java and Kotlin. Javalin started as a fork of the Spark framework but quickly turned into a ground-up rewrite influenced by express.js. Both of these web frameworks are inspired by the modern micro web framework grandfather: Sinatra, so if you’re coming from Ruby then Javalin shouldn’t feel too unfamiliar.

Flask and Javalin belong to "Microframeworks (Backend)" category of the tech stack.

Flask and Javalin are both open source tools. It seems that Flask with 45.2K GitHub stars and 12.7K forks on GitHub has more adoption than Javalin with 3.05K GitHub stars and 257 GitHub forks.

Advice on Flask and Javalin
Needs advice
Django REST frameworkDjango REST framework

Hey! So I am planning to make an e-commerce website with React Native as my frontend technology stack and MongoDB as my database. I was wondering what will be the best REST framework to use for my backend that will simply serve the frontend. Is Django rest framework a good option or should I go with Flask? I am currently leaning towards flask as the development team is well versed in it. Please help!

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Replies (2)
Mayur Borse
Software Engineer at hyphenOs · | 2 upvotes · 37.5K views

FastAPI is modern microframework. If you haven't used any of them, I'd suggest FastAPI. Django REST is also good if you have previous experience with it.

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Preeti Yuankrathok
Software Consultant at CODIUM · | 2 upvotes · 33.5K views

If the application is simple such as less endpoint or simple logic, I'd suggest Flask. But what you're building is quite a large system that contains many logics and a lot of models. So I'd suggest you with Django and Django REST framework. Django ORM is also one of the best ORM in the world as well.

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Senior Solutions Analyst · | 8 upvotes · 207.4K views

My journey to developing REST APIs started with Flask Restful, and I've found it to be enough for the needs of my project back then. Now that I've started investing more time on personal projects, I've yet to decide if I should move to use Django for writing REST APIs. I often see job posts looking for Python+Django developers, but it's usually for full-stack developers. I'm primarily interested in Data Engineering, so most of my web projects are back end.

Should I continue with what I know (Flask) or move on to Django?

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Replies (1)
Rafael Torres
Technical Lead at 4Agile · | 9 upvotes · 198.2K views

If you want to be a Web developer with knowledge in another frontend and NoSql technology, maybe continue with Flask. However, if you want to create very fast solutions to grow up with a new business and merge these with data analysis and other tools, Django is the answer. Basically read more about the service architecture where you feel more comfortable, Microservice or Monolithic, but please will not married with any because they solve issues to different contexts.

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Girish Sharma
Software Engineer at FireVisor Systems · | 6 upvotes · 160.5K views
Needs advice

Which is the best Python framework for microservices?

We are using Nameko for building microservices in Python. The things we really like are dependency injection and the ease with which one can expose endpoints via RPC over RabbitMQ. We are planning to try a tool that helps us write polyglot microservices and nameko is not super compatible with it. Also, we are a bit worried about the not so good community support from nameko and looking for a python alternate to write microservices.

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Replies (1)

Bottle is much less bloated and fast. Its built-in templating system is one of the fastest as it compiles the templates in bytecode. Also Bottle has no depenencies, preventing dependency bloat.

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Saurav Pandit
Application Devloper at Bny Mellon · | 5 upvotes · 164.3K views

I have just started learning Python 3 weeks ago. I want to create a REST API using python. The API will be used to save form data in an Oracle database. The front end is using AngularJS 8 with Angular Material. In python, there are so many frameworks to develop REST APIs.

I am looking for some suggestions which REST framework to choose?

Here are some features I am looking for:

  • Easy integration and unit testing, like in Angular. We just want to run a command.

  • Code packaging, like in java maven project we can build and package. I am looking for something which I can push in as an artifact and deploy whole code as a package.

  • Support for swagger/ OpenAPI

  • Support for JSON Web Token

  • Support for test case coverage report

Framework can have features included or can be available by extension. Also, you can suggest a framework other than the ones I have mentioned.

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Replies (1)

For starters flask provides a beautiful and easy way to create REST APIs. Also its supported by excellent beginner docs as well as a very active community. Another good thing with Flask is its widely available list of plugins which allow you to build as you go. Its also good in performance and can scale to a quite decent level. However, if you are sure your project is going to be fairly big, it would be better to start with Django as it provides a lot of features out of the box and is extremely stable in performance. Both these frameworks have support for Swagger, JWT, Coverage Report although you have to install plugins for them. Deploying both of these are fairly simple and there is huge documentation available. Django has one of the best documentations I have come across. I hope I was able to answer your queries.

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Decisions about Flask and Javalin

We decided to expose our small machine learning (ML) pipeline as a REST API. This allows us to nicely separate concerns from the rest of the codebase. There are two very popular choices in Python for building APIs: Flask and FastAPI. We have experience with both, but find that FastAPIs use of static type hints and validation with Pydantic allow us to build better APIs faster.

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Juan José Aguililla Martínez

I developed Hexagon heavily inspired in these great tools because of the following reasons:

  • Take full advantage of the Kotlin programming language without any strings attached to Java (as a language).
  • I wanted to be able to replace the HTTP server library used with different adapters (Jetty, Netty, etc.) and though right now there is only one, more are coming.
  • Have a complete tool to do full applications, though you can use other libraries, Hexagon comes with a dependency injection helper, settings loading from different sources and HTTP Client, so it comes with (batteries included).

Right now I'm using it for my pet projects, and I'm happy with it.

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Pros of Flask
Pros of Javalin
  • 314
  • 272
  • 215
  • 146
    Open source
  • 98
  • 66
    Easy to use
  • 54
    Easy to setup and get it going
  • 53
    Well designed
  • 48
    Easy to develop and maintain applications
  • 45
    Easy to get started
  • 18
    Beautiful code
  • 17
    Rapid development
  • 14
  • 13
  • 12
  • 12
  • 11
    Simple to use
  • 11
    Get started quickly
  • 11
  • 11
    Love it
  • 10
    Easy to integrate
  • 10
  • 9
    Perfect for small to large projects with superb docs.
  • 9
    For it flexibility
  • 8
    Flexibilty and easy to use
  • 8
  • 7
  • 6
    User friendly
  • 6
    Not JS
  • 5
  • 4
  • 1
  • 1
  • 1
    Rich support of template engines
  • 1
    Does not require IDEA plugins

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Cons of Flask
Cons of Javalin
  • 10
    Not JS
  • 7
  • 5
    Not fast
  • 1
    Don't has many module as in spring
    Be the first to leave a con

    Sign up to add or upvote consMake informed product decisions

    - No public GitHub repository available -

    What is Flask?

    Flask is intended for getting started very quickly and was developed with best intentions in mind.

    What is Javalin?

    Javalin started as a fork of the Spark framework but quickly turned into a ground-up rewrite influenced by express.js. Both of these web frameworks are inspired by the modern micro web framework grandfather: Sinatra, so if you’re coming from Ruby then Javalin shouldn’t feel too unfamiliar.

    Need advice about which tool to choose?Ask the StackShare community!

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    What companies use Javalin?
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    What tools integrate with Flask?
    What tools integrate with Javalin?

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    What are some alternatives to Flask and Javalin?
    Django is a high-level Python Web framework that encourages rapid development and clean, pragmatic design.
    By using non-blocking network I/O, Tornado can scale to tens of thousands of open connections, making it ideal for long polling, WebSockets, and other applications that require a long-lived connection to each user.
    Express is a minimal and flexible node.js web application framework, providing a robust set of features for building single and multi-page, and hybrid web applications.
    Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.
    Lots of people use React as the V in MVC. Since React makes no assumptions about the rest of your technology stack, it's easy to try it out on a small feature in an existing project.
    See all alternatives