TanStack Start is one of the most exciting full-stack web development frameworks I’ve seen. I’ve written about it before. In essence, TanStack Start takes TanStack Router, a superb, strongly-typed client-side JavaScript framework, and adds server-side support. This serves two purposes: it gives you a place to execute server-side code, like database access; and it enables […]

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TanStack Start's middleware feature enables executing code on both client and server before and after server-side operations, with data passing between them. The article demonstrates building a basic observability system using middleware to track server function execution with trace IDs, measuring end-to-end latency, and leveraging Node's AsyncLocalStorage to maintain context across nested server function calls. The middleware pattern allows splitting execution into client and server phases, each with before/after hooks, making it powerful for cross-cutting concerns like logging, authentication, and performance monitoring.

Introducing TanStack Start Middleware – Frontend Masters Blog