diff --git a/Gruntfile.js b/Gruntfile.js
index 4f4b3b027..dcb96a2c0 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -151,6 +151,7 @@ module.exports = function(grunt) {
                     "packages/node_modules/@node-red/editor-client/src/js/font-awesome.js",
                     "packages/node_modules/@node-red/editor-client/src/js/history.js",
                     "packages/node_modules/@node-red/editor-client/src/js/validators.js",
+                    "packages/node_modules/@node-red/editor-client/src/js/ui/mermaid.js",
                     "packages/node_modules/@node-red/editor-client/src/js/ui/utils.js",
                     "packages/node_modules/@node-red/editor-client/src/js/ui/common/editableList.js",
                     "packages/node_modules/@node-red/editor-client/src/js/ui/common/treeList.js",
@@ -225,7 +226,7 @@ module.exports = function(grunt) {
                         "node_modules/jsonata/jsonata-es5.min.js",
                         "packages/node_modules/@node-red/editor-client/src/vendor/jsonata/formatter.js",
                         "packages/node_modules/@node-red/editor-client/src/vendor/ace/ace.js",
-                        "packages/node_modules/@node-red/editor-client/src/vendor/ace/ext-language_tools.js",
+                        "packages/node_modules/@node-red/editor-client/src/vendor/ace/ext-language_tools.js"
                     ],
                     // "packages/node_modules/@node-red/editor-client/public/vendor/vendor.css": [
                     //     // TODO: resolve relative resource paths in
@@ -234,6 +235,9 @@ module.exports = function(grunt) {
                     "packages/node_modules/@node-red/editor-client/public/vendor/ace/worker-jsonata.js": [
                         "node_modules/jsonata/jsonata-es5.min.js",
                         "packages/node_modules/@node-red/editor-client/src/vendor/jsonata/worker-jsonata.js"
+                    ],
+                    "packages/node_modules/@node-red/editor-client/public/vendor/mermaid/mermaid.min.js": [
+                        "node_modules/mermaid/dist/mermaid.min.js"
                     ]
                 }
             }
diff --git a/package.json b/package.json
index ad65edd90..ed0edd2b0 100644
--- a/package.json
+++ b/package.json
@@ -109,6 +109,7 @@
         "jquery-i18next": "1.2.1",
         "jsdoc-nr-template": "github:node-red/jsdoc-nr-template",
         "marked": "4.2.3",
+        "mermaid": "^9.3.0",
         "minami": "1.2.3",
         "mocha": "9.2.2",
         "node-red-node-test-helper": "^0.3.0",
diff --git a/packages/node_modules/@node-red/editor-client/locales/en-US/editor.json b/packages/node_modules/@node-red/editor-client/locales/en-US/editor.json
index 27ccb1658..baaf338de 100755
--- a/packages/node_modules/@node-red/editor-client/locales/en-US/editor.json
+++ b/packages/node_modules/@node-red/editor-client/locales/en-US/editor.json
@@ -989,7 +989,10 @@
         "quote": "Quote",
         "link": "Link",
         "horizontal-rule": "Horizontal rule",
-        "toggle-preview": "Toggle preview"
+        "toggle-preview": "Toggle preview",
+        "mermaid": {
+            "summary": "Mermaid Diagram"
+        }
     },
     "bufferEditor": {
         "title": "Buffer editor",
diff --git a/packages/node_modules/@node-red/editor-client/locales/ja/editor.json b/packages/node_modules/@node-red/editor-client/locales/ja/editor.json
index c7b58b27f..478d2b950 100644
--- a/packages/node_modules/@node-red/editor-client/locales/ja/editor.json
+++ b/packages/node_modules/@node-red/editor-client/locales/ja/editor.json
@@ -989,7 +989,10 @@
         "quote": "引用",
         "link": "リンク",
         "horizontal-rule": "区切り線",
-        "toggle-preview": "プレビュー表示切替え"
+        "toggle-preview": "プレビュー表示切替え",
+        "mermaid": {
+            "summary": "Mermaid図"
+        }
     },
     "bufferEditor": {
         "title": "バッファエディタ",
diff --git a/packages/node_modules/@node-red/editor-client/src/js/ui/editors/markdown.js b/packages/node_modules/@node-red/editor-client/src/js/ui/editors/markdown.js
index 2d5368e96..bd7a11b3f 100644
--- a/packages/node_modules/@node-red/editor-client/src/js/ui/editors/markdown.js
+++ b/packages/node_modules/@node-red/editor-client/src/js/ui/editors/markdown.js
@@ -169,6 +169,7 @@
                             var currentScrollTop = $(".red-ui-editor-type-markdown-panel-preview").scrollTop();
                             $(".red-ui-editor-type-markdown-panel-preview").html(RED.utils.renderMarkdown(expressionEditor.getValue()));
                             $(".red-ui-editor-type-markdown-panel-preview").scrollTop(currentScrollTop);
+                            mermaid.init();
                         },200);
                     })
                     if (options.header) {
@@ -177,6 +178,7 @@
 
                     if (value) {
                         $(".red-ui-editor-type-markdown-panel-preview").html(RED.utils.renderMarkdown(expressionEditor.getValue()));
+                        mermaid.init();
                     }
                     panels = RED.panels.create({
                         id:"red-ui-editor-type-markdown-panels",
diff --git a/packages/node_modules/@node-red/editor-client/src/js/ui/mermaid.js b/packages/node_modules/@node-red/editor-client/src/js/ui/mermaid.js
new file mode 100644
index 000000000..d126cf188
--- /dev/null
+++ b/packages/node_modules/@node-red/editor-client/src/js/ui/mermaid.js
@@ -0,0 +1,46 @@
+// Mermaid diagram stub library for on-demand dynamic loading
+// Will be overwritten after script loading by $.getScript
+var mermaid = (function () {
+    var enabled /* = undefined */;
+    
+    var initializing = false;
+    var initCalled = false;
+
+    function initialize(opt) {
+        if (enabled === undefined) {
+            if (RED.settings.markdownEditor &&
+                RED.settings.markdownEditor.mermaid) {
+                enabled = RED.settings.markdownEditor.mermaid.enabled;
+            }
+            else {
+                enabled = true;
+            }
+        }
+        if (enabled) {
+            initializing = true;
+            $.getScript("vendor/mermaid/mermaid.min.js",
+                        function (data, stat, jqxhr) {
+                            $(".mermaid").show();
+                            // invoke loaded mermaid API
+                            initializing = false; 
+                            mermaid.initialize(opt);
+                            if (initCalled) {
+                                mermaid.init();
+                                initCalled = false;
+                            }
+                        });
+        }
+    }
+
+    function init() {
+        if (initializing) {
+            $(".mermaid").hide();
+            initCalled = true;
+        }
+    }
+    
+    return {
+        initialize: initialize,
+        init: init,
+    };
+})();
diff --git a/packages/node_modules/@node-red/editor-client/src/js/ui/tab-info.js b/packages/node_modules/@node-red/editor-client/src/js/ui/tab-info.js
index c46aa97e8..07818ffd2 100644
--- a/packages/node_modules/@node-red/editor-client/src/js/ui/tab-info.js
+++ b/packages/node_modules/@node-red/editor-client/src/js/ui/tab-info.js
@@ -463,7 +463,8 @@ RED.sidebar.info = (function() {
                     el = el.next();
                 }
                 $(this).toggleClass('expanded',!isExpanded);
-            })
+            });
+        mermaid.init();
     }
 
     var tips = (function() {
diff --git a/packages/node_modules/@node-red/editor-client/src/js/ui/utils.js b/packages/node_modules/@node-red/editor-client/src/js/ui/utils.js
index 2c4cdca6b..4d8ccdd9d 100644
--- a/packages/node_modules/@node-red/editor-client/src/js/ui/utils.js
+++ b/packages/node_modules/@node-red/editor-client/src/js/ui/utils.js
@@ -96,6 +96,37 @@ RED.utils = (function() {
         }
     }
 
+    var mermaidIsInitialized = false;
+    var mermaidIsEnabled /* = undefined */;
+
+    renderer.code = function (code, lang) {
+        if(lang === "mermaid") {
+            // mermaid diagram rendering 
+            if (mermaidIsEnabled === undefined) {
+                if (RED.settings.markdownEditor &&
+                    RED.settings.markdownEditor.mermaid) {
+                    mermaidIsEnabled = RED.settings.markdownEditor.mermaid.enabled;
+                }
+                else {
+                    mermaidIsEnabled = true;
+                }
+            }
+            if (mermaidIsEnabled) {
+                if (!mermaidIsInitialized) {
+                    mermaidIsInitialized = true;
+                    mermaid.initialize({startOnLoad:false});
+                }
+                return `<pre class='mermaid'>${code}</pre>`;
+            }
+            else {
+                return `<details><summary>${RED._("markdownEditor.mermaid.summary")}</summary><pre><code>${code}</code></pre></details>`;
+            }
+        }
+        else {
+            return "<pre><code>" +code +"</code></pre>";
+        }
+    };
+
     window._marked.setOptions({
         renderer: renderer,
         gfm: true,
diff --git a/packages/node_modules/@node-red/runtime/lib/api/settings.js b/packages/node_modules/@node-red/runtime/lib/api/settings.js
index 6c13596ce..2399a3152 100644
--- a/packages/node_modules/@node-red/runtime/lib/api/settings.js
+++ b/packages/node_modules/@node-red/runtime/lib/api/settings.js
@@ -89,10 +89,16 @@ var api = module.exports = {
 
         if (!runtime.settings.disableEditor) {
             safeSettings.context = runtime.nodes.listContextStores();
-            if (runtime.settings.editorTheme && runtime.settings.editorTheme.codeEditor) {
-                safeSettings.codeEditor = runtime.settings.editorTheme.codeEditor || {};
-                safeSettings.codeEditor.lib = safeSettings.codeEditor.lib || "monaco";
-                safeSettings.codeEditor.options = safeSettings.codeEditor.options || {};
+            if (runtime.settings.editorTheme) {
+                if (runtime.settings.editorTheme.codeEditor) {
+                    safeSettings.codeEditor = runtime.settings.editorTheme.codeEditor || {};
+                    safeSettings.codeEditor.lib = safeSettings.codeEditor.lib || "monaco";
+                    safeSettings.codeEditor.options = safeSettings.codeEditor.options || {};
+                }
+                if (runtime.settings.editorTheme.markdownEditor) {
+                    safeSettings.markdownEditor = runtime.settings.editorTheme.markdownEditor || {};
+                    safeSettings.markdownEditor.mermaid = safeSettings.markdownEditor.mermaid || { enabled: true };
+                }
             }
             safeSettings.libraries = runtime.library.getLibraries();
             if (util.isArray(runtime.settings.paletteCategories)) {
diff --git a/packages/node_modules/node-red/settings.js b/packages/node_modules/node-red/settings.js
index ec247a672..5d8a05e44 100644
--- a/packages/node_modules/node-red/settings.js
+++ b/packages/node_modules/node-red/settings.js
@@ -422,7 +422,16 @@ module.exports = {
                 //fontFamily: "Cascadia Code, Fira Code, Consolas, 'Courier New', monospace",
                 //fontLigatures: true,
             }
-        }
+        },
+
+        markdownEditor: {
+            mermaid: {
+                /** enable or disable mermaid diagram in markdown document
+                 */
+                enabled: true
+            }
+        },
+        
     },
 
 /*******************************************************************************