diff --git a/components/contribution-flow/index.js b/components/contribution-flow/index.js
index e4f7b38efcb..de10bc7873e 100644
--- a/components/contribution-flow/index.js
+++ b/components/contribution-flow/index.js
@@ -150,6 +150,8 @@ class ContributionFlow extends React.Component {
     LoggedInUser: PropTypes.object,
     createCollective: PropTypes.func.isRequired, // from mutation
     router: PropTypes.object,
+    onStepChange: PropTypes.func,
+    onSuccess: PropTypes.func,
   };
 
   constructor(props) {
@@ -444,6 +446,7 @@ class ContributionFlow extends React.Component {
     this.setState({ isSubmitted: true, isSubmitting: false });
     this.props.refetchLoggedInUser(); // to update memberships
     const queryParams = this.getQueryParams();
+    this.props.onSuccess?.(order);
     if (isValidExternalRedirect(queryParams.redirect)) {
       followOrderRedirectUrl(this.props.router, this.props.collective, order, queryParams.redirect, {
         shouldRedirectParent: queryParams.shouldRedirectParent,
@@ -658,6 +661,7 @@ class ContributionFlow extends React.Component {
 
     if (!this.state.error) {
       await this.pushStepRoute(step.name);
+      this.props.onStepChange?.(step.name);
     }
   };
 
diff --git a/pages/embed/contribution-flow.js b/pages/embed/contribution-flow.tsx
similarity index 65%
rename from pages/embed/contribution-flow.js
rename to pages/embed/contribution-flow.tsx
index 9932c083114..00a7b6a342a 100644
--- a/pages/embed/contribution-flow.js
+++ b/pages/embed/contribution-flow.tsx
@@ -1,13 +1,12 @@
 import React from 'react';
-import PropTypes from 'prop-types';
 import { graphql } from '@apollo/client/react/hoc';
-import { get } from 'lodash';
+import { get, omit, pick } from 'lodash';
 import { withRouter } from 'next/router';
 import { injectIntl } from 'react-intl';
 
-import { GQLV2_SUPPORTED_PAYMENT_METHOD_TYPES } from '../../lib/constants/payment-methods';
 import { generateNotFoundError, getErrorFromGraphqlException } from '../../lib/errors';
 import { API_V2_CONTEXT } from '../../lib/graphql/helpers';
+import { PaymentMethodLegacyType } from '../../lib/graphql/types/v2/schema';
 import { addParentToURLIfMissing } from '../../lib/url-helpers';
 
 import CollectiveThemeProvider from '../../components/CollectiveThemeProvider';
@@ -24,7 +23,17 @@ import Loading from '../../components/Loading';
 import { withStripeLoader } from '../../components/StripeProvider';
 import { withUser } from '../../components/UserProvider';
 
-class EmbedContributionFlowPage extends React.Component {
+class EmbedContributionFlowPage extends React.Component<{
+  router: any;
+  collectiveSlug: string;
+  tierId: number;
+  error: string;
+  queryParams: Record<string, unknown>;
+  loadStripe: () => void;
+  intl: any;
+  LoggedInUser: any;
+  data: Record<string, any>;
+}> {
   static getInitialProps({ query, res }) {
     if (res) {
       res.removeHeader('X-Frame-Options');
@@ -40,27 +49,6 @@ class EmbedContributionFlowPage extends React.Component {
     };
   }
 
-  static propTypes = {
-    collectiveSlug: PropTypes.string.isRequired,
-    tierId: PropTypes.number,
-    error: PropTypes.string,
-    data: PropTypes.shape({
-      loading: PropTypes.bool,
-      error: PropTypes.any,
-      account: PropTypes.object,
-      tier: PropTypes.object,
-    }), // from withData
-    intl: PropTypes.object,
-    loadStripe: PropTypes.func,
-    LoggedInUser: PropTypes.object,
-    loadingLoggedInUser: PropTypes.bool,
-    router: PropTypes.object,
-    queryParams: PropTypes.shape({
-      useTheme: PropTypes.bool,
-      backgroundColor: PropTypes.string,
-    }),
-  };
-
   componentDidMount() {
     this.loadExternalScripts();
     const { router, data } = this.props;
@@ -68,6 +56,8 @@ class EmbedContributionFlowPage extends React.Component {
     const path = router.asPath;
     const rawPath = path.replace(new RegExp(`^/embed/${account?.slug}/`), '/');
     addParentToURLIfMissing(router, account, rawPath, undefined, { prefix: '/embed' });
+    this.postMessage('initialized');
+    window.addEventListener('resize', this.onResize);
   }
 
   componentDidUpdate(prevProps) {
@@ -77,9 +67,34 @@ class EmbedContributionFlowPage extends React.Component {
     }
   }
 
+  componentWillUnmount(): void {
+    window.removeEventListener('resize', this.onResize);
+  }
+
+  onResize = () => {
+    this.postMessage('resized');
+  };
+
+  postMessage(event, payload = null) {
+    if (window.parent) {
+      try {
+        const size = { height: document.body.scrollHeight, width: document.body.scrollWidth };
+        const message = { event, size };
+        if (payload) {
+          message['payload'] = payload;
+        }
+
+        window.parent.postMessage(message, '*');
+      } catch (e) {
+        // eslint-disable-next-line no-console
+        console.error('Post message failed', e);
+      }
+    }
+  }
+
   loadExternalScripts() {
     const supportedPaymentMethods = get(this.props.data, 'account.host.supportedPaymentMethods', []);
-    if (supportedPaymentMethods.includes(GQLV2_SUPPORTED_PAYMENT_METHOD_TYPES.CREDIT_CARD)) {
+    if (supportedPaymentMethods.includes(PaymentMethodLegacyType.CREDIT_CARD)) {
       this.props.loadStripe();
     }
   }
@@ -93,10 +108,10 @@ class EmbedContributionFlowPage extends React.Component {
   }
 
   renderPageContent() {
-    const { data = {}, LoggedInUser } = this.props;
-    const { account, tier } = data;
+    const { data, LoggedInUser } = this.props;
+    const { account, tier, loading } = data || {};
 
-    if (data.loading) {
+    if (loading) {
       return (
         <Container py={[5, 6]}>
           <Loading />
@@ -116,6 +131,28 @@ class EmbedContributionFlowPage extends React.Component {
             host={account.host}
             tier={tier}
             error={this.props.error}
+            onStepChange={step =>
+              this.postMessage('stepChange', {
+                step,
+                height: document.body.scrollHeight,
+                width: document.body.scrollWidth,
+              })
+            }
+            onSuccess={order =>
+              this.postMessage('success', {
+                order: {
+                  id: order.id,
+                  legacyId: order.legacyId,
+                  status: order.status,
+                  frequency: order.frequency,
+                  amount: omit(order.amount, ['__typename']),
+                  platformTipAmount: omit(order.platformTipAmount, ['__typename']),
+                  tier: order.tier ? pick(order.tier, ['id']) : null,
+                  fromAccount: pick(order.fromAccount, ['id']),
+                  toAccount: pick(order.toAccount, ['id']),
+                },
+              })
+            }
           />
         </Box>
       );
@@ -141,7 +178,7 @@ class EmbedContributionFlowPage extends React.Component {
 }
 
 const addContributionFlowData = graphql(contributionFlowAccountQuery, {
-  options: props => ({
+  options: (props: { collectiveSlug: string; tierId: number }) => ({
     variables: { collectiveSlug: props.collectiveSlug, tierId: props.tierId, includeTier: Boolean(props.tierId) },
     context: API_V2_CONTEXT,
   }),
diff --git a/test/embed/contribution-flow.html b/test/embed/contribution-flow.html
new file mode 100644
index 00000000000..72fcd9731d8
--- /dev/null
+++ b/test/embed/contribution-flow.html
@@ -0,0 +1,159 @@
+<!-- A simple page for testing the embed contribution flow. Simply open it in your preferred browser. -->
+
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>OpenCollective Donation Embed Test</title>
+    <style>
+      body {
+        max-width: 80%;
+        margin: 20px auto;
+        padding: 0 20px;
+        font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif;
+        background-color: #f5f5f5;
+      }
+
+      #contributeIframe {
+        border-radius: 8px;
+        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
+        background-color: white;
+      }
+
+      #messages {
+        margin-top: 20px;
+        padding: 15px;
+        background-color: white;
+        border-radius: 8px;
+        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
+      }
+
+      #messages p {
+        margin: 10px 0;
+        padding: 10px;
+        background-color: #f8f9fa;
+        border-radius: 4px;
+        font-family: monospace;
+        white-space: pre-wrap;
+      }
+
+      .size-controls {
+        margin-bottom: 20px;
+      }
+
+      .size-controls button {
+        padding: 8px 16px;
+        margin-right: 10px;
+        border: 1px solid #ddd;
+        border-radius: 4px;
+        background-color: white;
+        cursor: pointer;
+        font-size: 14px;
+        transition: all 0.2s ease;
+      }
+
+      .size-controls button:hover {
+        background-color: #f0f0f0;
+        border-color: #bbb;
+      }
+
+      .size-controls button:active {
+        background-color: #e8e8e8;
+        transform: translateY(1px);
+      }
+
+      iframe {
+        resize: both;
+      }
+
+      .messages-title {
+        margin: 0 0 15px 0;
+        font-size: 1.2em;
+        font-weight: bold;
+      }
+
+      .no-messages {
+        color: #666;
+        font-style: italic;
+      }
+
+      #messagesList li {
+        animation: fadeIn 0.2s ease-in;
+      }
+
+      @keyframes fadeIn {
+        from {
+          opacity: 0;
+          transform: translateX(10px);
+        }
+        to {
+          opacity: 1;
+          transform: translateX(0);
+        }
+      }
+    </style>
+  </head>
+  <body>
+    <div class="size-controls">
+      <button onclick="setSize('mobile')">Mobile (320px)</button>
+      <button onclick="setSize('tablet')">Tablet (768px)</button>
+      <button onclick="setSize('desktop')">Desktop (100%)</button>
+    </div>
+
+    <iframe
+      id="contributeIframe"
+      src="http://localhost:3000/embed/apex/donate"
+      width="100%"
+      height="800px"
+      frameborder="0"
+    ></iframe>
+
+    <div id="messages">
+      <h2 class="messages-title">Channel messaging</h2>
+      <p class="no-messages">No messages exchanged yet</p>
+      <ul id="messagesList"></ul>
+    </div>
+
+    <script>
+      function addMessage(message) {
+        const messagesDiv = document.getElementById('messages');
+        const noMessages = messagesDiv.querySelector('.no-messages');
+        if (noMessages) {
+          noMessages.remove();
+        }
+
+        const messagesList = document.getElementById('messagesList');
+        const messageElement = document.createElement('li');
+        messageElement.textContent = message;
+        messagesList.appendChild(messageElement);
+      }
+
+      function setSize(device) {
+        const iframe = document.getElementById('contributeIframe');
+        switch (device) {
+          case 'mobile':
+            iframe.style.width = '320px';
+            break;
+          case 'tablet':
+            iframe.style.width = '768px';
+            break;
+          case 'desktop':
+            iframe.style.width = '100%';
+            break;
+        }
+      }
+
+      window.addEventListener('message', event => {
+        if (event.origin !== 'http://localhost:3000') return;
+        addMessage(`Message received: ${JSON.stringify(event.data)}`);
+      });
+
+      function sendMessageToIframe(message) {
+        const iframe = document.getElementById('contributeIframe');
+        iframe.contentWindow.postMessage(message, 'http://localhost:3000');
+        addMessage(`Message sent: ${JSON.stringify(message)}`);
+      }
+    </script>
+  </body>
+</html>