Inertia.js is a framework that lets you build modern single-page applications in React, Vue, or Svelte while keeping server-side routing and controllers.
The problem Inertia solves is the complexity of building single-page applications that typically require a separate API layer and frontend codebase. Instead of splitting your application into two systems, Inertia acts as a bridge between your existing backend framework and a modern frontend. Your server continues to handle routing, controllers, models, authorization, and validation as it normally would, but instead of returning HTML templates, it returns page components with their data. Inertia connects these two halves so that user interactions feel like a single-page application without full page reloads, while keeping everything in one codebase with one router and one source of truth.
You should consider Inertia if you want to add modern frontend interactivity to a server-side application without the overhead of building and maintaining a separate API. It works well for teams already comfortable with backend frameworks like Laravel, Rails, Phoenix, Django, Symfony, or others, who want to adopt React, Vue, or Svelte without restructuring their entire application. The tool is particularly suited to projects where you want the single-page experience your users expect but prefer to avoid the architectural complexity of decoupled frontend and backend systems. Inertia includes built-in support for forms with server-side validation, file uploads with progress tracking, optimistic updates, partial reloads, deferred props, prefetching, polling, infinite scroll, server-side rendering, code splitting, view transitions, and history encryption for sensitive data.
The project maintains active development across its core adapters for React, Vue, and Svelte, with an officially maintained Laravel adapter and community-contributed adapters for multiple server-side frameworks. The codebase includes comprehensive documentation covering installation through protocol internals, a demo application showcasing real-world usage patterns, and starter kits that provide working implementations with authentication and user management already configured.
