diff --git a/app/javascript/mastodon/actions/donate.ts b/app/javascript/mastodon/actions/donate.ts
new file mode 100644
index 00000000000..6246292081c
--- /dev/null
+++ b/app/javascript/mastodon/actions/donate.ts
@@ -0,0 +1,72 @@
+import { createAction } from '@reduxjs/toolkit';
+
+import { apiGetDonateData } from '../api/donate';
+import {
+  createAppThunk,
+  createDataLoadingThunk,
+} from '../store/typed_functions';
+
+import { focusCompose, resetCompose } from './compose';
+import { closeModal, openModal } from './modal';
+
+export const setDonateSeed = createAction<number>('donate/setSeed');
+
+export const initializeDonate = createAppThunk(
+  (_arg, { dispatch, getState }) => {
+    if (!getState().donate.seed) {
+      let seed = Math.floor(Math.random() * 99) + 1;
+      try {
+        const storedSeed = localStorage.getItem('donate_seed');
+        if (storedSeed) {
+          seed = Number.parseInt(storedSeed, 10);
+        } else {
+          localStorage.setItem('donate_seed', seed.toString());
+        }
+      } catch {
+        // No local storage available, just set a seed for this session.
+      }
+      dispatch(setDonateSeed(seed));
+    }
+    void dispatch(fetchDonateData());
+  },
+);
+
+export const fetchDonateData = createDataLoadingThunk(
+  'donate/fetch',
+  (_args: unknown, { getState }) => {
+    const state = getState();
+    return apiGetDonateData({
+      locale: state.meta.get('locale', 'en') as string,
+      seed: state.donate.seed ?? 1, // If we somehow don't have the seed, just set it to 1.
+    });
+  },
+  (data) => data, // This is needed for TypeScript to infer the correct overload.
+);
+
+export const showDonateModal = createAppThunk(
+  (_arg, { dispatch, getState }) => {
+    const state = getState();
+    const lastPoll = state.donate.nextPoll;
+    if (!lastPoll || Date.now() >= lastPoll) {
+      void dispatch(fetchDonateData());
+    }
+    dispatch(
+      openModal({
+        modalType: 'DONATE',
+        modalProps: {},
+      }),
+    );
+  },
+);
+
+export const composeDonateShare = createAppThunk(
+  (_arg, { dispatch, getState }) => {
+    const state = getState();
+    const shareText = state.donate.apiResponse?.donation_success_post;
+    if (shareText) {
+      dispatch(resetCompose());
+      dispatch(focusCompose(shareText));
+    }
+    dispatch(closeModal({ modalType: 'DONATE', ignoreFocus: false }));
+  },
+);
diff --git a/app/javascript/mastodon/api/donate.ts b/app/javascript/mastodon/api/donate.ts
new file mode 100644
index 00000000000..95c7381a70a
--- /dev/null
+++ b/app/javascript/mastodon/api/donate.ts
@@ -0,0 +1,30 @@
+import type {
+  DonateServerRequest,
+  DonateServerResponse,
+} from '../api_types/donate';
+
+// TODO: Proxy this through the backend.
+const API_URL = 'https://api.joinmastodon.org/v1/donations/campaigns/active';
+
+export const apiGetDonateData = async ({
+  locale,
+  seed,
+}: DonateServerRequest) => {
+  // Create the URL with query parameters.
+  const params = new URLSearchParams({
+    locale,
+    seed: seed.toString(),
+    platform: 'web',
+    source: 'menu',
+  });
+  const url = new URL(`${API_URL}?${params.toString()}`);
+
+  const response = await fetch(url);
+  if (!response.ok) {
+    throw new Error(`Error fetching donation campaign: ${response.statusText}`);
+  }
+  if (response.status === 204) {
+    return null;
+  }
+  return response.json() as Promise<DonateServerResponse>;
+};
diff --git a/app/javascript/mastodon/api_types/donate.ts b/app/javascript/mastodon/api_types/donate.ts
new file mode 100644
index 00000000000..45cf5bba79a
--- /dev/null
+++ b/app/javascript/mastodon/api_types/donate.ts
@@ -0,0 +1,23 @@
+export const donationFrequencyTypes = [
+  'one_time',
+  'monthly',
+  'yearly',
+] as const;
+export type DonationFrequency = (typeof donationFrequencyTypes)[number];
+
+export interface DonateServerRequest {
+  locale: string;
+  seed: number;
+}
+
+export interface DonateServerResponse {
+  id: string;
+  amounts: Record<DonationFrequency, Record<string, number[]>>;
+  donation_url: string;
+  banner_message: string;
+  banner_button_text: string;
+  donation_message: string;
+  donation_button_text: string;
+  donation_success_post: string;
+  default_currency: string;
+}
diff --git a/app/javascript/mastodon/features/ui/index.jsx b/app/javascript/mastodon/features/ui/index.jsx
index 0583bf99c5e..3b1a3fe6d97 100644
--- a/app/javascript/mastodon/features/ui/index.jsx
+++ b/app/javascript/mastodon/features/ui/index.jsx
@@ -11,6 +11,7 @@ import { connect } from 'react-redux';
 import { debounce } from 'lodash';
 
 import { focusApp, unfocusApp, changeLayout } from 'mastodon/actions/app';
+import { initializeDonate } from '@/mastodon/actions/donate';
 import { synchronouslySubmitMarkers, submitMarkers, fetchMarkers } from 'mastodon/actions/markers';
 import { fetchNotifications } from 'mastodon/actions/notification_groups';
 import { INTRODUCTION_VERSION } from 'mastodon/actions/onboarding';
@@ -394,6 +395,7 @@ class UI extends PureComponent {
       this.props.dispatch(expandHomeTimeline());
       this.props.dispatch(fetchNotifications());
       this.props.dispatch(fetchServerTranslationLanguages());
+      this.props.dispatch(initializeDonate());
 
       setTimeout(() => this.props.dispatch(fetchServer()), 3000);
     }
diff --git a/app/javascript/mastodon/reducers/donate.ts b/app/javascript/mastodon/reducers/donate.ts
new file mode 100644
index 00000000000..c9f1fc2ef41
--- /dev/null
+++ b/app/javascript/mastodon/reducers/donate.ts
@@ -0,0 +1,36 @@
+import { createReducer } from '@reduxjs/toolkit';
+
+import { fetchDonateData, setDonateSeed } from '../actions/donate';
+import type { DonateServerResponse } from '../api_types/donate';
+
+interface DonateState {
+  apiResponse?: DonateServerResponse;
+  nextPoll?: number;
+  isFetching: boolean;
+  seed?: number;
+}
+
+const initialState: DonateState = {
+  isFetching: false,
+};
+
+export const donateReducer = createReducer(initialState, (builder) => {
+  builder
+    .addCase(setDonateSeed, (state, action) => {
+      state.seed = action.payload;
+    })
+    .addCase(fetchDonateData.pending, (state) => {
+      state.isFetching = true;
+    })
+    .addCase(fetchDonateData.rejected, (state) => {
+      state.isFetching = false;
+    })
+    .addCase(fetchDonateData.fulfilled, (state, action) => {
+      if (action.payload) {
+        state.apiResponse = action.payload;
+      }
+      // If we have data, poll in four hours, otherwise try again in one hour.
+      state.nextPoll = Date.now() + 1000 * 60 * 60 * (action.payload ? 4 : 1);
+      state.isFetching = false;
+    });
+});
diff --git a/app/javascript/mastodon/reducers/index.ts b/app/javascript/mastodon/reducers/index.ts
index 19ecbbfff40..68cb4f23757 100644
--- a/app/javascript/mastodon/reducers/index.ts
+++ b/app/javascript/mastodon/reducers/index.ts
@@ -12,6 +12,7 @@ import { composeReducer } from './compose';
 import { contextsReducer } from './contexts';
 import conversations from './conversations';
 import custom_emojis from './custom_emojis';
+import { donateReducer } from './donate';
 import { dropdownMenuReducer } from './dropdown_menu';
 import filters from './filters';
 import height_cache from './height_cache';
@@ -43,6 +44,7 @@ import user_lists from './user_lists';
 
 const reducers = {
   announcements,
+  donate: donateReducer,
   dropdownMenu: dropdownMenuReducer,
   timelines,
   meta,