The Top 5 Python GUI Builders

Python is a popular language amongst beginners, academics and data scientists, and its popularity is steadily growing. In 2024, Python became the most used language on GitHub, surpassing JavaScript for the first time. With the number of Python developers steadily increasing, there is more demand than ever to be able to build graphical user interfaces (GUIs) with Python.

While Python has long been used as a backend language for web development, more and more developers are looking to use it on the frontend too. There are now several frameworks for building full-stack web applications entirely in Python, each with their own approach to solving the issue. Let’s take a look at a few of them.

In this article, we’ll compare and contrast five tools for building GUIs in Python:

  1. Streamlit
  2. Shiny for Python
  3. NiceGUI
  4. Reflex
  5. Anvil

TL;DR

Don’t have the time? Skip the in-depth comparison and go straight to the summary.

Streamlit

Streamlit is a popular open-source Python library for building data-driven apps. Streamlit’s approach to building web applications is simple and pythonic, which makes it easy to adapt existing Python scripts into Streamlit apps.

Screenshot of a Streamlit app showing data on NYC Uber pickups

An example Streamlit application showing data on New York City Uber pickups.

Although the Streamlit benefits from being straightforward and user friendly, its simplicity is also its biggest weakness. Any time a user interacts with a Streamlit app, the script reruns from top to bottom. This causes two issues: apps can be slow and state management is tricky. It’s also not easy to customize Streamlit apps, which results in most Streamlit apps all looking alike.

Overall, Streamlit is great for prototyping or building small data-based apps, but it’s not the best solution when your app requires more complexity or customization.

Pros

  • Easy to turn an existing script into an app
  • Great for building dashboards
  • Intuitive and straightforward to understand
  • Large and active developer community
  • Completely free and open-source

Cons

  • Apps can be slow
  • Not good for bigger, more complex apps
  • Hard to customize
  • Minimal features

Shiny for Python

Shiny for Python is a relatively new library for building interactive web applications in Python. Originally a popular tool for the language R, Shiny has now branched out into Python. Shiny’s approach is very similar to Streamlit’s, but it aims to correct two of Streamlit’s biggest flaws: the need to rerun the entire script and the lack of customizability.

An example Shiny dashboard: https://gallery.shinyapps.io/template-dashboard-tips1/

An example Shiny dashboard: https://gallery.shinyapps.io/template-dashboard-tips1/

Instead of reruning the entire script after any user interaction, Shiny only re-renders elements that have been affected by that user interaction. This means the entire Shiny script doesn’t need to rerun every time a user makes a change, but it leads to less readable and intuitive code.

Unlike Streamlit, Shiny also allows you to add CSS classes to have more control over the look and feel of your app.

Pros

  • The script doesn’t rerun after every user interaction
  • Can use CSS to customize your apps
  • Great for building dashboards
  • Good documentation and examples
  • Completely free and open-source

Cons

  • Less straightforward code
  • Minimal features
  • Newer library with a smaller community

NiceGUI

NiceGUI is Python library for building web applications that was developed explicitly as an alternative to Streamlit. Like Shiny for Python, NiceGUI doesn’t rerun the entire script after every user interaction. It also allows you to add CSS classes, including Tailwind classes, to your code for more customization of the look and feel.

NiceGUI’s website was built using NiceGUI.

NiceGUI’s website was built using NiceGUI.

NiceGUI code lacks the simplicity and intuitiveness of Streamlit code, and its approach to reactivity and state management is more opaque than Shiny’s. There are different methods and decorators for different types of UI updating, so it can be difficult to know how to get the UI to update. In addition, NiceGUI’s documentation is less robust than Streamlit’s or Shiny’s, and there are no tutorials or live examples. This makes getting started with NiceGUI more of a challenge.

Pros

  • The script doesn’t rerun after every user interaction
  • Can use inline CSS, stylesheets and Tailwind to customize your apps
  • Completely free and open-source

Cons

  • Incomplete documentation
  • No official tutorials
  • Not great for building dashboards
  • Updating the UI is not always straightforward or consistent

Reflex

While Reflex is also a Python library for building interactive GUIs, its approach is different than Streamlit, Shiny and NiceGUI. Unlike the previous options, Reflex doesn’t abstract away much of traditional web development. This means that if you are not familiar with traditional web development, Reflex comes with a bit of a learning curve. However, it also means that Reflex uses less magic to deal with reactivity and state management.

An example Reflex app: https://dashboard-new.reflex.run/

An example Reflex app: https://dashboard-new.reflex.run/

Reflex uses a State class to keep track of the state of the app, and methods within the State class update the app’s state. Although Reflex code is more verbose than the previous examples, it is more explicit about state management and separating front-end and back-end code. This means there is less “magic” involed in Reflex apps so they are easier to adapt and extend.

Pros

  • Explicit state management
  • Robust documentation with lots of examples
  • Templates to get started
  • Has an AI app generator
  • Customizable

Cons

  • Need to learn web development
  • Code is not that simple and straightforward

Anvil

Anvil takes a very different approach to building Python web applications. While the previous options are Python packages built as alternatives to Streamlit, Anvil was built to be Visual Basic for the web.

An example Anvil app. Learn more: https://anvil.works/learn/examples/task-manager-app

An example Anvil app. Learn more: https://anvil.works/learn/examples/task-manager-app

Anvil is a cloud-based IDE where you visually build your user interfaces and write Python code for the front-end and back-end. Like Reflex, Anvil doesn’t abstract away web development, but it aims to make it more approachable for non-web developers. To build an Anvil app, you drag and drop components onto the page to build your UI (you can also create components in code), then write client-side code to make the components interactive and server-side code for back-end functions. To call server functions from your UI, you just use anvil.server.call. Client-side code runs entirely in the browser which makes it super fast.

Anvil allows you to do everything in Python, but doesn’t try to stop you if you want to break out. You can still use HTML, CSS and JS in your Anvil apps. What’s more, Anvil includes a whole host of features that none of the other options having including a built-in database, out-of-the-box user management and instant cloud hosting.

Pros

  • Visually build your User Interface
  • Lots of built-in features and integrations
  • Instant unlimited cloud hosting
  • Explicit state management and separation of client and server
  • In-depth documentation and tutorials

Cons

  • Need to get used to a new IDE
  • Client-server architecture may be unfamiliar to non-web developers

Summary

  • Streamlit
    • Strengths: Quick to learn, straighforward code, easy for simple dashboards
    • Weakness: The entire script re-runs with user interaction, limited in features and flexibility
  • Shiny for Python
    • Strengths: Only re-runs relevant functions, great for building dashboards, good documentation and examples
    • Weaknesses: Newer library with a smaller community, minimal features
  • NiceGUI
    • Strengths: Doesn’t re-run the script after each interaction, can use CSS and Tailwind for customixation
    • Weaknesses: Code isn’t always straightforward, not great for dashboarding, incomplete documentation with no official tutorials
  • Reflex
    • Strengths: Uses explicit state management, very customizable, robust documentation and examples
    • Weaknesses: Larger learning curve, need to understand web development
  • Anvil
    • Strengths: Out-of-the-box instant cloud hosting , drag-and-drop UI builder, more features for complex apps, in-depth documentation with lots of tutorials
    • Weaknesses: Unfamiliar IDE, client-server architecture may be unfamiliar as well

Conclusion

With Python being the most popular programming language, there are more tools than ever for building interactive web applications entirely in Python.

Streamlit is one such tool that offers a simple, Pythonic approach. However, it suffers from two main weaknesses: the script needs to be re-run after every user interaction, and customizing the look and feel of a Streamlit app is dificult. Shiny for Python is a great alternative for building dashboards and small data-backed apps. Shiny only re-renders code as necessary - not the entire script, and offers more flexibility in styling your app. NiceGUI offers a similar approach, but with less intuitive code and no tutorials or live examples, is more of a challenge to get started with. Reflex is a great option if you want more flexibility in building your app’s UI, but you’ll need to learn a bit of traditional web development.

Anvil takes a different approach to building Python web apps. With Anvil, you drag and drop components to build your user interface then write Python code to make it interactive. Anvil also comes with many out-of-the-box features such as a built-in database, user management and instant cloud hosting. If you want to build more complex apps and host them easily for free, then Anvil is your best bet.


More about Anvil

If you’re new here, welcome! Anvil is a platform for building full-stack web apps with nothing but Python. No need to wrestle with JS, HTML, CSS, Python, SQL and all their frameworks – just build it all in Python.

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Nothing but Python required!
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