Streamlit

Streamlit lets data scientists turn a plain Python script into an interactive web app by adding a handful of function calls — sliders, buttons, charts, file uploads — with no HTML, CSS, or JavaScript involved. Every rerun of the script re-renders the app top to bottom, which keeps the mental model simple even as the app grows.

It’s become the default way to demo a model, share an internal dashboard, or wrap a data pipeline in something non-technical stakeholders can actually click around in. The open-source library is free; Streamlit Community Cloud offers free hosting for public apps.