diff --git a/babel.config.js b/babel.config.js
index 750b6bb718..9b32fff363 100644
--- a/babel.config.js
+++ b/babel.config.js
@@ -81,6 +81,10 @@ module.exports = (api) => {
             // we require polyfills for this already
             'Array.prototype.includes',
 
+            // Used only in Chat, which expects modern browsers
+            'Object.fromEntries',
+            'Object.entries',
+
             // false positive (babel doesn't know types)
             // this is actually only called on arrays
             'String.prototype.includes',
diff --git a/package.json b/package.json
index 547614229d..088eb7bd28 100644
--- a/package.json
+++ b/package.json
@@ -136,6 +136,7 @@
     "rollup-plugin-node-resolve": "5.2.0",
     "rollup-plugin-replace": "2.2.0",
     "rollup-plugin-uglify": "6.0.4",
+    "rollup-plugin-alias": "2.2.0",
     "shelljs": "0.8.5",
     "shipjs": "0.26.0",
     "ts-jest": "27",
diff --git a/packages/instantsearch.js/scripts/rollup/emptyModule.js b/packages/instantsearch.js/scripts/rollup/emptyModule.js
new file mode 100644
index 0000000000..9a699f1102
--- /dev/null
+++ b/packages/instantsearch.js/scripts/rollup/emptyModule.js
@@ -0,0 +1,12 @@
+// Placeholder export for 'eventsource-parser' module
+export const EventSourceParserStream = {};
+
+// Placeholder export for 'zod' module
+export const ZodFirstPartyTypeKind = {};
+export const z = {};
+export const toJSONSchema = {};
+export const safeParseAsync = {};
+
+// Placeholder export for 'react' module
+export const cloneElement = {};
+export const createElement = {};
diff --git a/packages/instantsearch.js/scripts/rollup/rollup.config.js b/packages/instantsearch.js/scripts/rollup/rollup.config.js
index fc29baf117..902c76616e 100644
--- a/packages/instantsearch.js/scripts/rollup/rollup.config.js
+++ b/packages/instantsearch.js/scripts/rollup/rollup.config.js
@@ -1,3 +1,6 @@
+import path from 'path';
+
+import alias from 'rollup-plugin-alias';
 import babel from 'rollup-plugin-babel';
 import commonjs from 'rollup-plugin-commonjs';
 import filesize from 'rollup-plugin-filesize';
@@ -16,6 +19,22 @@ const link = 'https://github.com/algolia/instantsearch';
 const license = `/*! InstantSearch.js ${version} | ${algolia} | ${link} */`;
 
 const plugins = [
+  alias({
+    entries: [
+      {
+        find: /^zod.*/,
+        replacement: path.join(__dirname, './emptyModule.js'),
+      },
+      {
+        find: /^eventsource-parser.*/,
+        replacement: path.join(__dirname, './emptyModule.js'),
+      },
+      {
+        find: /^react.*/,
+        replacement: path.join(__dirname, './emptyModule.js'),
+      },
+    ],
+  }),
   resolve({
     browser: true,
     preferBuiltins: false,
diff --git a/packages/instantsearch.js/src/index.ts b/packages/instantsearch.js/src/index.ts
index c47a0dc424..b99879f2e1 100644
--- a/packages/instantsearch.js/src/index.ts
+++ b/packages/instantsearch.js/src/index.ts
@@ -1,4 +1,4 @@
-import * as connectors from './connectors/index.umd';
+import * as connectors from './connectors/index';
 import * as helpers from './helpers/index';
 import { createInfiniteHitsSessionStorageCache } from './lib/infiniteHitsCache/index';
 import InstantSearch from './lib/InstantSearch';
@@ -7,7 +7,7 @@ import * as stateMappings from './lib/stateMappings/index';
 import version from './lib/version';
 import * as middlewares from './middlewares/index';
 import * as templates from './templates/index';
-import * as widgets from './widgets/index.umd';
+import * as widgets from './widgets/index';
 
 import type { InstantSearchOptions } from './lib/InstantSearch';
 import type { Expand, UiState } from './types';
diff --git a/yarn.lock b/yarn.lock
index 76e8c8cb88..31d94cf828 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -26487,7 +26487,7 @@ react@17.0.1:
     loose-envify "^1.1.0"
     object-assign "^4.1.1"
 
-"react@>= 0.14.0", react@19.0.0:
+react@19.0.0, "react@>= 0.14.0":
   version "19.0.0"
   resolved "https://registry.yarnpkg.com/react/-/react-19.0.0.tgz#6e1969251b9f108870aa4bff37a0ce9ddfaaabdd"
   integrity sha512-V8AVnmPIICiWpGfm6GLzCR/W5FXLchHop40W4nXBmdlEceh16rCN8O8LNWm5bh5XUX91fh7KpA+W0TgMKmgTpQ==
@@ -27522,6 +27522,13 @@ ripemd160@^2.0.0, ripemd160@^2.0.1:
     hash-base "^2.0.0"
     inherits "^2.0.1"
 
+rollup-plugin-alias@2.2.0:
+  version "2.2.0"
+  resolved "https://registry.yarnpkg.com/rollup-plugin-alias/-/rollup-plugin-alias-2.2.0.tgz#5004a2bc542a2eebb45b5a0fff8c6f540439decc"
+  integrity sha512-9ZK410qeFed4gGrHoojBpxLsHF74vPgsheGg9JRW5RbALAxqdvJbd357mSqWBqUrBfRVnZnNUXTZdYLxxQEA5A==
+  dependencies:
+    slash "^3.0.0"
+
 rollup-plugin-babel@4.3.3:
   version "4.3.3"
   resolved "https://registry.yarnpkg.com/rollup-plugin-babel/-/rollup-plugin-babel-4.3.3.tgz#7eb5ac16d9b5831c3fd5d97e8df77ba25c72a2aa"