AstroPatterns is a course that allows you to practice building fullstack applications directly in your browser without needing to install anything on your computer. The course is based on exercises where you can learn how to fix problems and then practice on a real application. The user interface includes a code editor with code samples, a button to check the solution, and a preview of a running Astro application. You can edit the code in real-time and see the changes happen instantly. The course is currently in beta-test phase, and you can reach out to the creator at [email protected] to join. For more information and troubleshooting, check out the WebContainers documentation. Additionally, there is a Next.js course available at NextPatterns.dev. Explore the hidden gems of AstroPatterns and start building amazing fullstack applications today!