Keep your app
Reuse React Router route objects and components. Add the SSR plugin and entries to your Vite project.
Keep your Vite config, route objects and components. Add SSR without moving to Framework mode or rewriting the app.

@lomray/vite-ssr-boost adds SSR to Vite apps using React Router Data mode. You keep route objects and choose how to run the server. The package does not implement React Server Components, Server Actions or file-system routing conventions.
For an existing app, add SsrBoost() to the Vite plugins, use @lomray/vite-ssr-boost/browser/entry in the browser entry and @lomray/vite-ssr-boost/adapters/express/entry in the server entry. Create a new app with npm create @lomray/ssr-app@latest my-app to start from the minimal template. The CLI handles development, HMR, SSR builds and SPA builds. Use the Fetch core and runtime adapters when your application needs to own the transport and its asset integration.