RTK Query vs TanStack Query (and when to use which)

What RTK Query is

From the official docs: RTK Query lives inside @reduxjs/toolkit as a separate entry point. It removes hand-written fetch/cache logic and stores its cache in Redux.

Import createApi from @reduxjs/toolkit/query/react to get auto-generated React hooks.

Docs rule of thumb: one API slice per base URL.

import { createApi, fetchBaseQuery } from "@reduxjs/toolkit/query/react";

export const api = createApi({
  reducerPath: "api",
  baseQuery: fetchBaseQuery({ baseUrl: "/api" }),
  endpoints: (build) => ({
    getTickets: build.query<Ticket[], void>({
      query: () => "/tickets",
    }),
    createTicket: build.mutation<Ticket, NewTicket>({
      query: (body) => ({ url: "/tickets", method: "POST", body }),
    }),
  }),
});

export const { useGetTicketsQuery, useCreateTicketMutation } = api;
// Also add api.reducer + api.middleware to configureStore

What this monorepo chooses

TanStack Query + Axios withCredentials for Nest HTTP lists.

RTK createSlice for client drafts that are not server truth yet.

Do not run RTK Query and TanStack Query for the same Nest list.

Client draft text     → RTK createSlice
Nest list / detail    → TanStack Query (+ Axios)
Nest auth cookie      → browser httpOnly + Nest guards
Other codebases       → often RTK Query createApi

// Wrong
useGetNotesQuery();
useQuery({ queryKey: ["notes"], queryFn: list });

// Right here
useNotesQuery(); // TanStack only

Interview one-liners

“RTK is modern Redux: configureStore, createSlice, thunks, entity adapters, selectors.”

“RTK Query is the fetching addon in the same package; TanStack Query is a separate server-state library.”

“On this project: RTK for client drafts, TanStack Query for Nest HTTP.”

RTK core = client shared state
RTK Query = optional Redux-powered server cache
TanStack Query = our Nest server cache

Keep in mind

• RTK Query Quick Start via Tutorials Overview: https://redux-toolkit.js.org/tutorials/overview
• Learn createApi so foreign codebases make sense.
• Ship Nest features here with TanStack Query + RTK drafts (Week 4 Notes projects).