TanStack Start is a full-stack web framework for React and Solid from TanStack, an open-source project owned by TanStack LLC. A full-stack framework covers both the browser part of a web application and the server part that renders pages and answers requests. Start is built on TanStack Router, a type-safe router (the code that maps each URL to a page, checked by TypeScript), and on the Vite or Rsbuild build tools.
Start adds a server layer around the router's route tree. It gives full-document SSR (server-side rendering: the server sends finished HTML, and the browser then hydrates it, which means it attaches the interactive code) and streaming, which sends a page in parts as its data becomes ready. Server functions are type-safe RPCs (remote procedure calls) from the browser code to the server; server routes answer outside callers; middleware handles authentication, logging and similar checks. The same code builds for different hosts, such as Vercel, Netlify, Cloudflare or a Node.js server.
Start is open source under the MIT license and free to use. Partner companies and sponsors fund the work.