Show HN: Full Python GUI apps in the browser – no JavaScript, no server (opens in new tab)

(github.com)

20 pointspstomi4d ago7 comments

I have been working on Dear ImGui Bundle since 2022, but it is the first time I talk about it here. It is a framework around Dear ImGui for building interactive applications in Python and C++. It comes with batteries included: Plotting, image inspection, Markdown, node editors, 3D gizmos, knobs, toggles, etc.

https://imgui-bundle.pages.dev

It now also runs smoothly in the browser via pyodide: The playground below is a python app running in your browser (no server, no JavaScript). You can edit the code on the left and click Run. It even works on mobile.

https://imgui-bundle.pages.dev/playground

I have a strong interest in providing tools that help others express their creativity. This project aims to be a step in this direction as it helps develop GUIs where the code is extremely readable & hackable.

Some of the goals it addresses:

- Bring true Immediate Mode GUI to Python and C++

- A versatile range of high quality libraries: Widgets, Plots, Image Analysis, Node edition, markdown rendering

- Multiplatform apps in C++: works on all platform in C++ (desktop, mobile, emscripten)

- Deploy python apps to the web

- High quality python bindings that are always up-to-date (because they are auto-generated)

- Smooth transition between C++ and Python (same APIs for both)

I'd be happy to answer questions!

7 comments

austin-cheney4d ago

I agree with the other comments. Its super cool after it eventually loads.

For real world use I don't think its practical if its only goal is basic browser UX in Python versus JavaScript, but I can see amazing value in this for larger applications written in Python that need to make use of a Python GUI.

pstomiOP4d ago

Absolutely. This shines when you actually want to display complex / animated / streaming data in larger applications; or if you want to create educative or training material on several pages (i.e apps here).

As an example, I once built an online stock/ticker app with it: smooth real-time updates in a nice plot. It would have been more complex with DOM based widgets (and probably less fun).

2ndorderthought4d ago

Is this downloading and installing Python packages into the browser via wasm?

I like the idea a little bit. Mostly because I don't like javascript. So I say keep going for it, it could fill some niches.

I'm sure you know this, but the page takes like 30s to load on mobile. It wasn't a comfortable ux. Once it did load it seemed pretty fast though so kudos. Kind of gave me macromedia flash vibes from 2002.

pstomiOP4d ago

Thanks! I don't like javascript either, and I certainly dislike CSS :-)

Yes, the initial download of pyodide is about 5 MB. After that it is another 5MB for the bundle wheel.

But there is some hope: Based on test I just did, I see I did not setup headers so that the wheel and pyodide are cached in a browser (or in its fs): this could reduce reload times by a sizable factor.

Once loaded you can run at 60 FPS (or even 120 FPS depending on the browser's vsync).

As you can see in the playground: you can then switch from app to app instantly once pyodide is loaded and running. It almost feels like going from a page to another. You can see that when using the combobox to select example at the top right in the playground.

gloflo4d ago

If no JavaScript then what enables interactivity?

pstomiOP4d ago

Thanks for the question! I should have said almost no JavaScript:

There is a minimal amount of JavaScript just to download and run pyodide and then it is only Python: see example at

https://imgui-bundle.pages.dev/playground/?demo=p_35_minimal...

fredcallagan4d ago

Very very impressive! So many use cases for this. Thanks again

hagbard_c4d ago

Web assembly? This started out as a bowdlerised form of JavaScript (asm.js) but evolved to become is own thing.

sheept4d ago

You still need JavaScript to instantiate WebAssembly and let it interact with the page, which is why your sibling comment admits there's still a bit of JS.

j / k navigate · click thread line to collapse

7 comments

austin-cheney4d ago

I agree with the other comments. Its super cool after it eventually loads.

pstomiOP4d ago

As an example, I once built an online stock/ticker app with it: smooth real-time updates in a nice plot. It would have been more complex with DOM based widgets (and probably less fun).

2ndorderthought4d ago

Is this downloading and installing Python packages into the browser via wasm?

I like the idea a little bit. Mostly because I don't like javascript. So I say keep going for it, it could fill some niches.

pstomiOP4d ago

Thanks! I don't like javascript either, and I certainly dislike CSS :-)

Yes, the initial download of pyodide is about 5 MB. After that it is another 5MB for the bundle wheel.

Once loaded you can run at 60 FPS (or even 120 FPS depending on the browser's vsync).

gloflo4d ago

If no JavaScript then what enables interactivity?

pstomiOP4d ago

Thanks for the question! I should have said almost no JavaScript:

There is a minimal amount of JavaScript just to download and run pyodide and then it is only Python: see example at

https://imgui-bundle.pages.dev/playground/?demo=p_35_minimal...

fredcallagan4d ago

Very very impressive! So many use cases for this. Thanks again

hagbard_c4d ago

Web assembly? This started out as a bowdlerised form of JavaScript (asm.js) but evolved to become is own thing.

sheept4d ago

You still need JavaScript to instantiate WebAssembly and let it interact with the page, which is why your sibling comment admits there's still a bit of JS.

j / k navigate · click thread line to collapse