diff --git a/tests/multi_playground.html b/tests/multi_playground.html
index da48e2c85..3a2720818 100644
--- a/tests/multi_playground.html
+++ b/tests/multi_playground.html
@@ -4,14 +4,13 @@
 <meta charset="utf-8">
 <title>Multi-toolbox Playground</title>
 
-<!-- This script loads uncompressed when on localhost and loads compressed when it is being hosted.
-     Please add any other dependencies to playgrounds/load_all.js.-->
-<script src="playgrounds/load_all.js"></script>
+<!-- This script loads uncompressed when on localhost and loads
+     compressed when it is being hosted or on Internet Explorer.  -->
+<script src="bootstrap.js"></script>
+<script type=module>
+import Blockly from './blockly.mjs';
 
-<script>
-'use strict';
-
-const IS_UNCOMPRESSED = !!document.getElementById('blockly-uncompressed-script');
+const IS_UNCOMPRESSED = Boolean(window.BlocklyLoader);  // See bootstrap.js
 
 var options = {
   comments: true,
@@ -74,6 +73,12 @@ function setBackgroundColour() {
     document.body.style.backgroundColor = '#60fcfc';  // Unfamiliar blue.
   }
 }
+
+// Call start().  Because this <script> has type=module, it is
+// automatically deferred, so it will not be run until after the
+// document has been parsed, but before firing DOMContentLoaded.
+start();
+
 </script>
 
 <style>
@@ -105,7 +110,7 @@ h1 {
 }
 </style>
 </head>
-<body onload="start()">
+<body>
   <h1>Blockly Multi Playground</h1>
 
   <form id="options">
diff --git a/tests/playgrounds/load_all.js b/tests/playgrounds/load_all.js
deleted file mode 100644
index 5eaa65e03..000000000
--- a/tests/playgrounds/load_all.js
+++ /dev/null
@@ -1,53 +0,0 @@
-/**
- * @license
- * Copyright 2021 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-
-/**
- * @fileoverview Loads uncompressed Blockly when running locally. Loads
- * compressed otherwise.
- */
-'use strict';
-
-
-/**
- * Loads all the compressed or uncompressed dependencies necessary to run the
- * playground. This is necessary since the goog.module conversion. Please see
- * issue #5557 for more information.
- */
-(function() {
-const isIe = navigator.userAgent.indexOf('MSIE') !== -1 ||
-    navigator.appVersion.indexOf('Trident/') > -1;
-
-if ((location.hostname === 'localhost' || location.hostname === '127.0.0.1' ||
-     location.hostname === '[::1]') &&
-    !isIe) {
-  document.write(
-      `<script src="../blockly_uncompressed.js" id="blockly-uncompressed-script"></script>`);
-  document.write(`<script src="../msg/messages.js"></script>`);
-  document.write(`<script src="../tests/themes/test_themes.js"></script>`);
-  document.write(
-      `<script src="../node_modules/@blockly/block-test/dist/index.js"></script>`);
-  document.write(`<script>
-                // Custom requires for the playground.
-                goog.require('Blockly.libraryBlocks');
-                goog.require('Blockly.Dart.all');
-                goog.require('Blockly.JavaScript.all');
-                goog.require('Blockly.Lua.all');
-                goog.require('Blockly.PHP.all');
-                goog.require('Blockly.Python.all');
-                goog.require('Blockly.WorkspaceCommentSvg');
-            </script>`);
-} else {
-  document.write(
-      `<script src="../blockly_compressed.js" id="blockly-compressed-script"></script>`);
-  document.write(`<script src="../blocks_compressed.js"></script>`);
-  document.write(`<script src="../dart_compressed.js"></script>`);
-  document.write(`<script src="../javascript_compressed.js"></script>`);
-  document.write(`<script src="../lua_compressed.js"></script>`);
-  document.write(`<script src="../php_compressed.js"></script>`);
-  document.write(`<script src="../python_compressed.js"></script>`);
-  document.write(`<script src="../msg/messages.js"></script>`);
-}
-})();
