React 19 server actions delete your whole API layer

React 19 Server Actions let you mark an async function "use server" and hand it straight to a form. That one function replaces your REST endpoint, your fetch wrapper, and your React Query mutation. Three new hooks add loading states, errors, and optimistic UI. Both Next.js App Router and TanStack Start ship it, so forms rarely need an API layer. Key Takeaways Your forms submit even before the…