Next.js is an open-source web development framework created by Vercel enabling React-based web applications with server-side-rendering and generating static websites.
React documentation mentions Next.js among "Recommended Toolchains" advising it to developers as a solution when "Building a server-rendered website with Node.js". Where traditional React apps can only render their content in the client-side browser, Next.js extends this functionality to include applications rendered on the server-side.