diff --git a/Editor/Scripts/MarkdownWindow.cs b/Editor/Scripts/MarkdownWindow.cs
new file mode 100644
index 0000000..1f42338
--- /dev/null
+++ b/Editor/Scripts/MarkdownWindow.cs
@@ -0,0 +1,260 @@
+using System.IO;
+using UnityEditor;
+using UnityEngine;
+using UnityEditor.Callbacks;
+
+namespace MG.MDV
+{
+    public class MarkdownWindow : EditorWindow
+    {
+        private TextAsset mMarkdownFile;
+        private string mLoadedContent;
+        private MarkdownViewer mViewer;
+        private Vector2 mScrollPosition;
+        private bool mSyncSelection = true;
+
+        private GUISkin mSkinLight;
+        private GUISkin mSkinDark;
+
+        [MenuItem("Window/Markdown Viewer Window")]
+        public static void ShowWindow()
+        {
+            var window = GetWindow<MarkdownWindow>("Markdown Viewer");
+            window.Show();
+        }
+
+        [OnOpenAsset(1)]
+        public static bool OnOpenAsset(int instanceID, int line)
+        {
+            var obj = EditorUtility.InstanceIDToObject(instanceID);
+            if (obj is TextAsset textAsset)
+            {
+                var path = AssetDatabase.GetAssetPath(textAsset);
+                var ext = Path.GetExtension(path).ToLower();
+                if (ext == ".md" || ext == ".markdown")
+                {
+                    var window = GetWindow<MarkdownWindow>("Markdown Viewer");
+                    window.LoadMarkdownFile(textAsset);
+                    window.Show();
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        private void OnEnable()
+        {
+            LoadSkins();
+            EditorApplication.update += UpdateRequests;
+            
+            if (mMarkdownFile != null)
+            {
+                ReloadCurrentFile();
+            }
+            else if (Selection.activeObject is TextAsset textAsset)
+            {
+                var path = AssetDatabase.GetAssetPath(textAsset);
+                var ext = Path.GetExtension(path).ToLower();
+                if (ext == ".md" || ext == ".markdown")
+                {
+                    LoadMarkdownFile(textAsset);
+                }
+            }
+        }
+
+        private void OnDisable()
+        {
+            EditorApplication.update -= UpdateRequests;
+            mViewer = null;
+        }
+
+        private void UpdateRequests()
+        {
+            if (mViewer != null && mViewer.Update())
+            {
+                Repaint();
+            }
+
+            // Auto-reload if file contents changed on disk
+            if (mMarkdownFile != null && mMarkdownFile.text != mLoadedContent)
+            {
+                ReloadCurrentFile();
+            }
+        }
+
+        private void OnSelectionChange()
+        {
+            if (mSyncSelection)
+            {
+                if (Selection.activeObject is TextAsset textAsset)
+                {
+                    var path = AssetDatabase.GetAssetPath(textAsset);
+                    var ext = Path.GetExtension(path).ToLower();
+                    if (ext == ".md" || ext == ".markdown")
+                    {
+                        LoadMarkdownFile(textAsset);
+                        Repaint();
+                    }
+                }
+            }
+        }
+
+        public void LoadMarkdownFile(TextAsset file)
+        {
+            if (mMarkdownFile == file && mViewer != null)
+            {
+                return;
+            }
+
+            mMarkdownFile = file;
+            ReloadCurrentFile();
+        }
+
+        private void ReloadCurrentFile()
+        {
+            LoadSkins();
+
+            if (mMarkdownFile != null)
+            {
+                var path = AssetDatabase.GetAssetPath(mMarkdownFile);
+                mLoadedContent = mMarkdownFile.text;
+                var skin = Preferences.DarkSkin ? mSkinDark : mSkinLight;
+                mViewer = new MarkdownViewer(skin, path, mLoadedContent, () => position.width);
+            }
+            else
+            {
+                mViewer = null;
+                mLoadedContent = null;
+            }
+        }
+
+        private void LoadSkins()
+        {
+            if (mSkinLight == null)
+            {
+                var path = AssetDatabase.GUIDToAssetPath("81f272e4a921a5448a30c0e40b4ea003");
+                if (!string.IsNullOrEmpty(path))
+                {
+                    mSkinLight = AssetDatabase.LoadAssetAtPath<GUISkin>(path);
+                }
+            }
+            if (mSkinDark == null)
+            {
+                var path = AssetDatabase.GUIDToAssetPath("8611e9e5923b6084997203d4997b4976");
+                if (!string.IsNullOrEmpty(path))
+                {
+                    mSkinDark = AssetDatabase.LoadAssetAtPath<GUISkin>(path);
+                }
+            }
+        }
+
+        private void OnGUI()
+        {
+            DrawToolbar();
+
+            if (mMarkdownFile == null)
+            {
+                DrawDragAndDropZone();
+                return;
+            }
+
+            if (mViewer == null)
+            {
+                ReloadCurrentFile();
+            }
+
+            if (mViewer == null)
+            {
+                EditorGUILayout.HelpBox("Failed to initialize Markdown Viewer.", MessageType.Error);
+                return;
+            }
+
+            mScrollPosition = EditorGUILayout.BeginScrollView(mScrollPosition);
+            mViewer.Draw();
+            EditorGUILayout.EndScrollView();
+        }
+
+        private void DrawToolbar()
+        {
+            using (new EditorGUILayout.HorizontalScope(EditorStyles.toolbar))
+            {
+                var newFile = (TextAsset)EditorGUILayout.ObjectField(mMarkdownFile, typeof(TextAsset), false, GUILayout.Width(250));
+                if (newFile != mMarkdownFile)
+                {
+                    if (newFile == null)
+                    {
+                        LoadMarkdownFile(null);
+                    }
+                    else
+                    {
+                        var path = AssetDatabase.GetAssetPath(newFile);
+                        var ext = Path.GetExtension(path).ToLower();
+                        if (ext == ".md" || ext == ".markdown")
+                        {
+                            LoadMarkdownFile(newFile);
+                        }
+                    }
+                }
+
+                GUILayout.Space(5);
+
+                mSyncSelection = GUILayout.Toggle(mSyncSelection, "Sync Selection", EditorStyles.toolbarButton);
+
+                GUILayout.FlexibleSpace();
+
+                if (GUILayout.Button("Reload", EditorStyles.toolbarButton))
+                {
+                    ReloadCurrentFile();
+                }
+
+                if (GUILayout.Button("Clear", EditorStyles.toolbarButton))
+                {
+                    LoadMarkdownFile(null);
+                }
+            }
+        }
+
+        private void DrawDragAndDropZone()
+        {
+            var rect = GUILayoutUtility.GetRect(0, 0, GUILayout.ExpandWidth(true), GUILayout.ExpandHeight(true));
+            GUI.Box(rect, "Drag and drop a Markdown (.md) file here", new GUIStyle(GUI.skin.box)
+            {
+                alignment = TextAnchor.MiddleCenter,
+                fontSize = 14,
+                normal = { textColor = Color.gray }
+            });
+
+            var evt = Event.current;
+            switch (evt.type)
+            {
+                case EventType.DragUpdated:
+                case EventType.DragPerform:
+                    if (!rect.Contains(evt.mousePosition))
+                        break;
+
+                    DragAndDrop.visualMode = DragAndDropVisualMode.Copy;
+
+                    if (evt.type == EventType.DragPerform)
+                    {
+                        DragAndDrop.AcceptDrag();
+                        foreach (var draggedObject in DragAndDrop.objectReferences)
+                        {
+                            if (draggedObject is TextAsset textAsset)
+                            {
+                                var path = AssetDatabase.GetAssetPath(textAsset);
+                                var ext = Path.GetExtension(path).ToLower();
+                                if (ext == ".md" || ext == ".markdown")
+                                {
+                                    LoadMarkdownFile(textAsset);
+                                    Repaint();
+                                    break;
+                                }
+                            }
+                        }
+                    }
+                    evt.Use();
+                    break;
+            }
+        }
+    }
+}
diff --git a/Editor/Scripts/MarkdownWindow.cs.meta b/Editor/Scripts/MarkdownWindow.cs.meta
new file mode 100644
index 0000000..d45c569
--- /dev/null
+++ b/Editor/Scripts/MarkdownWindow.cs.meta
@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: ecd1fe6ba17648143a9f5dc9db49ae2a
\ No newline at end of file