Modern State Management in Scalable React Applications

As frontend applications grow, managing complex data flows becomes one of the biggest challenges. "Put everything in a Redux store" used to be the standard approach. In modern web engineering, though, classifying data by its nature and managing it accordingly is an architectural necessity.

Client State vs. Server State

On the high-traffic Fintech and e-commerce (B2C/B2B) platforms I've built, making this distinction correctly is the single most critical rule I apply.

1. Server State: Data that comes from an API (user profile, product list, bank transactions). It requires synchronization, caching, and stale-time management.
2. Client State: Data that only lives in the browser (whether a modal is open, dark mode, the selected tab).

For Server State: TanStack Query (React Query)

Keeping server data inside Redux leads to unnecessary boilerplate and synchronization bugs. TanStack Query takes that entire burden off your hands.

import { useQuery } from "@tanstack/react-query";

function useTransactions() {
  return useQuery({
    queryKey: ["transactions"],
    queryFn: async () => {
      const res = await fetch("/api/transactions");
      return res.json();
    },
    staleTime: 1000 * 60 * 5, // don't refetch for 5 minutes
  });
}