Nuxt is a free and open source JavaScript library based on Vue.js, Nitro, and Vite. Nuxt is inspired by Next.js, which is a similar framework based on React rather than Vue.
The main advantage of Nuxt over using Vue alone is its universal rendering system. The framework works as both an in-browser single page application (SPA) as well as a server-rendered static website, by "hydrating" a server-rendered page to a full SPA after it's loaded. This allows websites to have the SEO and performance benefits of a server-rendered site in addition to the interactivity of a client-rendered application. Nuxt largely abstracts the server-rendering features from the developer, and it's therefore able to have a similar development experience to a traditional SPA using Vue's single file component (SFC) system.
In addition to its flagship universal rendering mechanism, Nuxt also provides many other benefits and quality-of-life features, such as path-based routing, hot module replacement (HMR), TypeScript support out of the box, and middleware and server logic.