router-core/ssr

Create a shared router factory used by both entries, then build a server entry with createRequestHandler and defaultRenderHandler or defaultStreamHandler, and a client entry that calls hydrateRoot with RouterClient. Loaders are automatically dehydrated on the server and hydrated on the client.

Non-streaming SSR renders the full page on the server and sends one HTML response via renderRouterToString. Streaming SSR sends the critical first paint immediately and streams remaining content incrementally via renderRouterToStream or defaultStreamHandler.

Yes, with SSR enabled loaders run on both client and server, but they are not server-only like Remix or Next.js loaders. Browser-only APIs such as window or localStorage must be guarded with an environment check to avoid server crashes.

Yes, createRequestHandler expects a Web API Request and returns a Web API Response, so Express integration requires converting req into a Request and piping the response body back with node stream pipelines. A complete adapter example is provided in the documentation.

Hash fragments are never sent to the server, so conditional rendering based on window.location.hash differs between server and client output. Use validated search params instead so the state is visible during server rendering.

TanStack Start is the recommended way to do SSR in production because the manual SSR APIs are experimental and share internal implementations that may change. Use manual setup only when integrating with an existing server.