PyScript lets you run Python scripts right in the browser, side by side with JavaScript, with two-way interaction between your code and the web page.

It's possible to take a step further with a browser extension, but this is a basic Python project that hosts a web page that you can drag and drop a file on for a visualizer.

Python might be the most popular programming language in the world, but unlike other frontrunner JavaScript, you can't run Python code in the browser.