I build this using Next.js, React, and Tailwind CSS. The app allows users to create a workout routine and track their progress over time. To handle authentication, I used Next-Auth which provides options to log in using Discord or Google. I used Prisma as an ORM and a PostgreSQL database to store user data. The app also includes analytics tracking using Vercel Analytics. For type-safe communication between the client and server, I used TRPC.