Building web apps is a complicated mess. You need to know Python, JS, HTML, CSS, SQL, Flask, Bootstrap, SQLAlchemy, Webpack...the list goes on. What if you could do it all in Python? That's what we built: an open-source framework with Python in the browser, Python on the server - even a Python UI toolkit. And then we built an online IDE, drag'n'drop designer and hosting platform for it - all available for free. In this talk, I'm going to discuss the current web landscape, why we built Anvil the way we did - then take a deep dive into how it works, including a live demo. How do you run Python in the browser? How do you build an autocompleter that knows about everything from your UI layout to your database schema? And what does it mean for a programming tool to be "accessible"? No web development knowledge is required, and no paid features of Anvil are showcased in this talk.