Next Twitter is built using the frontend (& backend) React framework Next.js v13 with the new App Router and Server Actions. Everything is built within Next.js, including the backend for fetching posts and what not.
Regarding authentication, the easiest solution for Next Twitter is to use the popular NextAuth (now Auth.js) library for OAuth with Google, allowing for a smooth and seamless experience when logging in and posting away.
Prisma gives the power to create database tables and queries without having to touch SQL, as well as being able to run in serverless environments. In combination with Planetscale, these two powerful backend features made Next Twitter possible.
Finally, the component library used to make the frontend of Next Twitter is NextUI v2 with Tailwind. They have some beautiful components and transitions between dark and light theme to make your experience better!