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.

PyScript, which is, of course, Python in the browser. The tool is in the early experimental phase, so the project doesn’t suggest using it in a production environment yet.

Playwright, a Python library, allows developers to essentially control the browser with a few lines of Python code to automate cross-browser testing for single-page web apps and Progressive Web Apps.

A new project from Anaconda delivers the Python runtime in a web page, via a single JS include, and with access to many popular Python packages.

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.