diff --git a/main/app.ts b/main/app.ts
new file mode 100644
index 0000000..111b436
--- /dev/null
+++ b/main/app.ts
@@ -0,0 +1,169 @@
+import * as path from 'path';
+import {app, BrowserWindow, globalShortcut, Tray} from 'electron';
+import windowState = require('electron-window-state');
+import * as menubar from 'menubar';
+import log from './log';
+import {Config} from './config'
+
+const IS_DEBUG = process.env.NODE_ENV === 'development';
+const IS_DARWIN = process.platform === 'darwin';
+const APP_ICON = path.join(__dirname, '..', 'resources', 'icon.png');
+const DEFAULT_WIDTH = 340;
+const DEFAULT_HEIGHT = 400;
+
+export class App {
+    private host: string;
+
+    constructor(private win: Electron.BrowserWindow, private config: Config) {
+        if (config.accounts.length === 0) {
+            throw new Error('No account found. Please check the config.');
+        }
+        this.host = this.config.accounts[0].host;
+    }
+
+    open() {
+        this.win.loadURL(`https://${this.host}`);
+        this.win.show();
+    }
+}
+
+function trayIcon(color: string) {
+    return path.join(__dirname, '..', 'resources', `tray-icon-${
+        color === 'white' ? 'white' : 'black'
+    }@2x.png`);
+}
+
+export default function startApp (config: Config) {
+    return (config.normal_window ? startNormalWindow : startMenuBar)(config)
+        .then(win => new App(win, config));
+}
+
+function startNormalWindow(config: Config): Promise<Electron.BrowserWindow> {
+    log.debug('Setup a normal window');
+    return new Promise<Electron.BrowserWindow>(resolve => {
+        const state = windowState({
+            defaultWidth: 600,
+            defaultHeight: 800,
+        });
+        const win = new BrowserWindow({
+            width: state.width,
+            height: state.height,
+            x: state.x,
+            y: state.y,
+            icon: APP_ICON,
+            show: false,
+            useContentSize: true,
+            autoHideMenuBar: true,
+            webPreferences: {
+                nodeIntegration: false,
+                sandbox: true,
+            },
+        });
+        win.once('ready-to-show', () => {
+            win.show();
+        });
+        win.once('closed', () => {
+            app.quit();
+        });
+
+        if (state.isFullScreen) {
+            win.setFullScreen(true);
+        } else if (state.isMaximized) {
+            win.maximize();
+        }
+        state.manage(win);
+
+        const toggleWindow = () => {
+            if (win.isFocused()) {
+                log.debug('Toggle window: shown -> hidden');
+                if (IS_DARWIN) {
+                    app.hide();
+                } else {
+                    win.hide();
+                }
+            } else {
+                log.debug('Toggle window: hidden -> shown');
+                win.show();
+            }
+        };
+
+        win.webContents.on('dom-ready', () => {
+            log.debug('Send config to renderer procress');
+            win.webContents.send('mstdn:config', config);
+        });
+        win.webContents.once('dom-ready', () => {
+            log.debug('Normal window application was launched');
+            if (config.hot_key) {
+                globalShortcut.register(config.hot_key, toggleWindow);
+                log.debug('Hot key was set to:', config.hot_key);
+            }
+            if (IS_DEBUG) {
+                win.webContents.openDevTools({mode: 'detach'});
+            }
+            resolve(win);
+        });
+
+        const normalIcon = trayIcon(config.icon_color);
+        const tray = new Tray(normalIcon);
+        tray.on('click', toggleWindow);
+        tray.on('double-click', toggleWindow);
+        if (IS_DARWIN) {
+            tray.setHighlightMode('never');
+        }
+    });
+}
+
+function startMenuBar(config: Config): Promise<Electron.BrowserWindow> {
+    log.debug('Setup a menubar window');
+    return new Promise<Electron.BrowserWindow>(resolve => {
+        const state = windowState({
+            defaultWidth: DEFAULT_WIDTH,
+            defaultHeight: DEFAULT_HEIGHT,
+        });
+        const icon = trayIcon(config.icon_color);
+        const mb = menubar({
+            icon,
+            width: state.width,
+            height: state.height,
+            alwaysOnTop: IS_DEBUG || !!config.always_on_top,
+            tooltip: 'Mstdn',
+            showDockIcon: true,
+            autoHideMenuBar: true,
+            useContentSize: true,
+            show: false,
+            webPreferences: {
+                nodeIntegration: false,
+                sandbox: true,
+            },
+        });
+        mb.once('ready', () => mb.showWindow());
+        mb.once('after-create-window', () => {
+            log.debug('Menubar application was launched');
+            if (config.hot_key) {
+                globalShortcut.register(config.hot_key, () => {
+                    if (mb.window.isFocused()) {
+                        log.debug('Toggle window: shown -> hidden');
+                        mb.hideWindow();
+                    } else {
+                        log.debug('Toggle window: hidden -> shown');
+                        mb.showWindow();
+                    }
+                });
+                log.debug('Hot key was set to:', config.hot_key);
+            }
+            if (IS_DEBUG) {
+                mb.window.webContents.openDevTools({mode: 'detach'});
+            }
+            mb.window.webContents.on('dom-ready', () => {
+                log.debug('Send config to renderer procress');
+                mb.window.webContents.send('mstdn:config', config);
+            });
+            state.manage(mb.window);
+
+            resolve(mb.window);
+        });
+        mb.once('after-close', () => {
+            app.quit();
+        });
+    });
+}
diff --git a/main/config.ts b/main/config.ts
new file mode 100644
index 0000000..f615291
--- /dev/null
+++ b/main/config.ts
@@ -0,0 +1,68 @@
+import {app, systemPreferences} from 'electron';
+import * as fs from 'fs';
+import {join} from 'path';
+import log from './log';
+
+export interface Account {
+    host: string;
+    name: string;
+}
+
+export interface Config {
+    hot_key: string;
+    icon_color: string;
+    always_on_top: boolean;
+    normal_window: boolean;
+    zoom_factor: number;
+    accounts: Account[];
+    keymaps: {[key: string]: string};
+}
+
+function makeDefaultConfig(): Config {
+    const IsDarkMode = (process.platform === 'darwin') && systemPreferences.isDarkMode();
+    const menubarBroken = process.platform === 'win32';
+
+    return {
+        hot_key: 'CmdOrCtrl+Shift+S',
+        icon_color: IsDarkMode ? 'white' : 'black',
+        always_on_top: false,
+        normal_window: menubarBroken,
+        zoom_factor: 1.0,
+        accounts: [],
+        keymaps: {},
+    };
+}
+
+export default function loadConfig(): Promise<Config> {
+    return new Promise<Config>(resolve => {
+        const dir = app.getPath('userData');
+        const file = join(dir, 'config.json');
+        fs.readFile(file, 'utf8', (err, json) => {
+            if (err) {
+                log.info('Configuration file was not found, will create:', file);
+                const default_config = makeDefaultConfig();
+                // Note:
+                // If calling writeFile() directly here, it tries to create config file before Electron
+                // runtime creates data directory. As the result, writeFile() would fail to create a file.
+                if (app.isReady()) {
+                    fs.writeFile(file, JSON.stringify(default_config, null, 2));
+                } else {
+                    app.once('ready', () => fs.writeFile(file, JSON.stringify(default_config, null, 2)));
+                }
+                return resolve(default_config);
+            }
+
+            try {
+                const config = JSON.parse(json);
+                if (config.hot_key && config.hot_key.startsWith('mod+')) {
+                    config.hot_key = `CmdOrCtrl+${config.hot_key.slice(4)}`;
+                }
+                log.debug('Configuration was loaded successfully', config);
+                resolve(config);
+            } catch (e) {
+                log.error('Error on loading JSON file, will load default configuration:', e.message);
+                resolve(makeDefaultConfig());
+            }
+        });
+    });
+}
diff --git a/main/index.ts b/main/index.ts
new file mode 100644
index 0000000..a4d5a70
--- /dev/null
+++ b/main/index.ts
@@ -0,0 +1,22 @@
+import {app} from 'electron';
+import log from './log';
+import startApp from './app';
+import loadConfig from './config';
+
+const appReady = new Promise<void>(resolve => app.once('ready', resolve));
+
+process.on('unhandledRejection', (reason: string) => {
+    log.error('FATAL: Unhandled rejection! Reason:', reason);
+});
+
+app.on('will-quit', () => {
+    log.debug('Application is quitting');
+});
+
+Promise.all([
+    loadConfig(),
+    appReady
+]).then(([config, _]) => startApp(config)).then(win => {
+    win.open();
+    log.debug('Application launched!');
+});
diff --git a/main/log.ts b/main/log.ts
new file mode 100644
index 0000000..29e118f
--- /dev/null
+++ b/main/log.ts
@@ -0,0 +1,9 @@
+import * as log from 'loglevel';
+
+if (process.env.NODE_ENV === 'development') {
+    log.setLevel('debug');
+} else {
+    log.setLevel('info');
+}
+
+export default log;
diff --git a/package.json b/package.json
index aae7afa..8d06f7b 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "mstdn",
   "productName": "Mstdn",
-  "version": "0.0.0",
+  "version": "0.0.1",
   "description": "Tiny web-based mastodon client for your desktop",
   "main": "main/index.js",
   "bin": {
@@ -35,6 +35,7 @@
   "devDependencies": {
     "@types/electron": "^1.4.35",
     "@types/electron-window-state": "^2.0.28",
+    "@types/loglevel": "^1.4.29",
     "@types/mousetrap": "^1.5.33",
     "@types/node": "^7.0.12",
     "electron-packager": "^8.6.0",
@@ -46,7 +47,7 @@
     "electron": "^1.6.2",
     "electron-window-state": "^4.1.1",
     "loglevel": "^1.4.1",
-    "menubar": "github:rhysd/menubar#rhysd-fixes",
+    "menubar": "github:rhysd/menubar#mstdn",
     "mousetrap": "^1.6.1"
   }
 }