GatsbyJS is a free and open-source static site generator based on React. It uses a modern development stack including Webpack, GraphQL, and modern JavaScript and CSS frameworks. It also provides a rich set of plugins, starters, and themes.

Next.js is a React-based web framework that enables server-side rendering, static site generation, and other powerful features for building modern web applications.

Vercel offers built-in support for deploying and hosting Next.js applications, making it a popular choice among Next.js developers.