diff --git a/app/commands.js b/app/commands.ts
similarity index 91%
rename from app/commands.js
rename to app/commands.ts
index a5e5acb6..4b5fdf15 100644
--- a/app/commands.js
+++ b/app/commands.ts
@@ -1,9 +1,9 @@
-import {app, Menu} from 'electron';
+import {app, Menu, BrowserWindow} from 'electron';
 import {openConfig, getConfig} from './config';
 import {updatePlugins} from './plugins';
 import {installCLI} from './utils/cli-install';
 
-const commands = {
+const commands: Record<string, (focusedWindow?: BrowserWindow) => void> = {
   'window:new': () => {
     // If window is created on the same tick, it will consume event too
     setTimeout(app.createWindow, 0);
@@ -31,7 +31,7 @@ const commands = {
     focusedWindow && focusedWindow.rpc.emit('session clear req');
   },
   'editor:selectAll': focusedWindow => {
-    focusedWindow.rpc.emit('term selectAll');
+    focusedWindow && focusedWindow.rpc.emit('term selectAll');
   },
   'plugins:update': () => {
     updatePlugins();
@@ -112,20 +112,20 @@ const commands = {
   },
   'window:hamburgerMenu': () => {
     if (getConfig().showHamburgerMenu) {
-      Menu.getApplicationMenu().popup({x: 15, y: 15});
+      Menu.getApplicationMenu()!.popup({x: 15, y: 15});
     }
   }
 };
 
 //Special numeric command
-[1, 2, 3, 4, 5, 6, 7, 8, 'last'].forEach(cmdIndex => {
+([1, 2, 3, 4, 5, 6, 7, 8, 'last'] as const).forEach(cmdIndex => {
   const index = cmdIndex === 'last' ? cmdIndex : cmdIndex - 1;
   commands[`tab:jump:${cmdIndex}`] = focusedWindow => {
     focusedWindow && focusedWindow.rpc.emit('move jump req', index);
   };
 });
 
-export const execCommand = (command, focusedWindow) => {
+export const execCommand = (command: string, focusedWindow?: BrowserWindow) => {
   const fn = commands[command];
   if (fn) {
     fn(focusedWindow);
diff --git a/app/config/import.js b/app/config/import.ts
similarity index 91%
rename from app/config/import.js
rename to app/config/import.ts
index 0fd65668..d98f4bfa 100644
--- a/app/config/import.js
+++ b/app/config/import.ts
@@ -4,13 +4,13 @@ import {defaultCfg, cfgPath, legacyCfgPath, plugs, defaultPlatformKeyPath} from
 import {_init, _extractDefault} from './init';
 import notify from '../notify';
 
-let defaultConfig;
+let defaultConfig: Record<string, any> | undefined;
 
-const _write = (path, data) => {
+const _write = (path: string, data: any) => {
   // This method will take text formatted as Unix line endings and transform it
   // to text formatted with DOS line endings. We do this because the default
   // text editor on Windows (notepad) doesn't Deal with LF files. Still. In 2017.
-  const crlfify = str => {
+  const crlfify = (str: string) => {
     return str.replace(/\r?\n/g, '\r\n');
   };
   const format = process.platform === 'win32' ? crlfify(data.toString()) : data;
@@ -19,7 +19,7 @@ const _write = (path, data) => {
 
 // Saves a file as backup by appending '.backup' or '.backup2', '.backup3', etc.
 // so as to not override any existing files
-const saveAsBackup = src => {
+const saveAsBackup = (src: string) => {
   let attempt = 1;
   while (attempt < 100) {
     try {
@@ -99,7 +99,7 @@ const _importConf = () => {
     // Importing platform specific keymap
     try {
       const content = readFileSync(defaultPlatformKeyPath(), 'utf8');
-      const mapping = JSON.parse(content);
+      const mapping = JSON.parse(content) as Record<string, string | string[]>;
       _defaultCfg.keymaps = mapping;
     } catch (err) {
       //eslint-disable-next-line no-console
@@ -122,14 +122,14 @@ const _importConf = () => {
 
 export const _import = () => {
   const imported = _importConf();
-  defaultConfig = imported.defaultCfg;
-  const result = _init(imported);
+  defaultConfig = imported?.defaultCfg;
+  const result = _init(imported!);
   return result;
 };
 
 export const getDefaultConfig = () => {
   if (!defaultConfig) {
-    defaultConfig = _extractDefault(_importConf().defaultCfg);
+    defaultConfig = _importConf()?.defaultCfg;
   }
   return defaultConfig;
 };
diff --git a/app/config/init.js b/app/config/init.ts
similarity index 79%
rename from app/config/init.js
rename to app/config/init.ts
index c84d1f93..561103f7 100644
--- a/app/config/init.js
+++ b/app/config/init.ts
@@ -2,16 +2,16 @@ import vm from 'vm';
 import notify from '../notify';
 import mapKeys from '../utils/map-keys';
 
-const _extract = script => {
-  const module = {};
-  script.runInNewContext({module});
+const _extract = (script?: vm.Script): Record<string, any> => {
+  const module: Record<string, any> = {};
+  script?.runInNewContext({module});
   if (!module.exports) {
     throw new Error('Error reading configuration: `module.exports` not set');
   }
   return module.exports;
 };
 
-const _syntaxValidation = cfg => {
+const _syntaxValidation = (cfg: string) => {
   try {
     return new vm.Script(cfg, {filename: '.hyper.js', displayErrors: true});
   } catch (err) {
@@ -19,12 +19,12 @@ const _syntaxValidation = cfg => {
   }
 };
 
-const _extractDefault = cfg => {
+const _extractDefault = (cfg: string) => {
   return _extract(_syntaxValidation(cfg));
 };
 
 // init config
-const _init = cfg => {
+const _init = (cfg: {userCfg: string; defaultCfg: Record<string, any>}) => {
   const script = _syntaxValidation(cfg.userCfg);
   if (script) {
     const _cfg = _extract(script);
diff --git a/app/config/open.js b/app/config/open.ts
similarity index 84%
rename from app/config/open.js
rename to app/config/open.ts
index 4352cabe..63779bce 100644
--- a/app/config/open.js
+++ b/app/config/open.ts
@@ -5,12 +5,12 @@ export default () => Promise.resolve(shell.openItem(cfgPath));
 // Windows opens .js files with  WScript.exe by default
 // If the user hasn't set up an editor for .js files, we fallback to notepad.
 if (process.platform === 'win32') {
-  const Registry = require('winreg');
-  const {exec} = require('child_process');
+  const Registry = require('winreg') as typeof import('winreg');
+  const {exec} = require('child_process') as typeof import('child_process');
 
   const getUserChoiceKey = async () => {
     // Load FileExts keys for .js files
-    const keys = await new Promise((resolve, reject) => {
+    const keys: Winreg.Registry[] = await new Promise((resolve, reject) => {
       new Registry({
         hive: Registry.HKCU,
         key: '\\Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\FileExts\\.js'
@@ -29,11 +29,11 @@ if (process.platform === 'win32') {
   };
 
   const hasDefaultSet = async () => {
-    let userChoice = await getUserChoiceKey();
+    const userChoice = await getUserChoiceKey();
     if (!userChoice) return false;
 
     // Load key values
-    let values = await new Promise((resolve, reject) => {
+    const values: string[] = await new Promise((resolve, reject) => {
       userChoice.values((error, items) => {
         if (error) {
           reject(error);
@@ -51,7 +51,7 @@ if (process.platform === 'win32') {
   };
 
   // This mimics shell.openItem, true if it worked, false if not.
-  const openNotepad = file =>
+  const openNotepad = (file: string) =>
     new Promise(resolve => {
       exec(`start notepad.exe ${file}`, error => {
         resolve(!error);
diff --git a/app/config/paths.js b/app/config/paths.ts
similarity index 96%
rename from app/config/paths.js
rename to app/config/paths.ts
index 2d59d913..000826b2 100644
--- a/app/config/paths.js
+++ b/app/config/paths.ts
@@ -20,7 +20,7 @@ const applicationDirectory =
 
 let cfgDir = applicationDirectory;
 let cfgPath = join(applicationDirectory, cfgFile);
-let legacyCfgPath = join(homeDirectory, cfgFile); // Hyper 2 config location
+const legacyCfgPath = join(homeDirectory, cfgFile); // Hyper 2 config location
 
 const devDir = resolve(__dirname, '../..');
 const devCfg = join(devDir, cfgFile);
diff --git a/app/config/windows.js b/app/config/windows.ts
similarity index 84%
rename from app/config/windows.js
rename to app/config/windows.ts
index 2706c500..0486fdf4 100644
--- a/app/config/windows.js
+++ b/app/config/windows.ts
@@ -1,4 +1,5 @@
 import Config from 'electron-store';
+import {BrowserWindow} from 'electron';
 
 const defaults = {
   windowPosition: [50, 50],
@@ -15,7 +16,7 @@ export default {
     const size = cfg.get('windowSize');
     return {position, size};
   },
-  recordState(win) {
+  recordState(win: BrowserWindow) {
     cfg.set('windowPosition', win.getPosition());
     cfg.set('windowSize', win.getSize());
   }
diff --git a/app/rpc.ts b/app/rpc.ts
index 5f9f39b4..3b562830 100644
--- a/app/rpc.ts
+++ b/app/rpc.ts
@@ -36,7 +36,7 @@ export class Server extends EventEmitter {
     super.emit(ev, data);
   }
 
-  emit(ch: string, data: any): any {
+  emit(ch: string, data: any = {}): any {
     // This check is needed because data-batching can cause extra data to be
     // emitted after the window has already closed
     if (!this.win.isDestroyed()) {
diff --git a/app/ui/contextmenu.js b/app/ui/contextmenu.ts
similarity index 50%
rename from app/ui/contextmenu.js
rename to app/ui/contextmenu.ts
index 481e130f..be004062 100644
--- a/app/ui/contextmenu.js
+++ b/app/ui/contextmenu.ts
@@ -2,26 +2,30 @@ import editMenu from '../menus/menus/edit';
 import shellMenu from '../menus/menus/shell';
 import {execCommand} from '../commands';
 import {getDecoratedKeymaps} from '../plugins';
-const separator = {type: 'separator'};
+import {MenuItemConstructorOptions, BrowserWindow} from 'electron';
+const separator: MenuItemConstructorOptions = {type: 'separator'};
 
-const getCommandKeys = keymaps =>
-  Object.keys(keymaps).reduce((commandKeys, command) => {
+const getCommandKeys = (keymaps: Record<string, string[]>): Record<string, string> =>
+  Object.keys(keymaps).reduce((commandKeys: Record<string, string>, command) => {
     return Object.assign(commandKeys, {
       [command]: keymaps[command][0]
     });
   }, {});
 
 // only display cut/copy when there's a cursor selection
-const filterCutCopy = (selection, menuItem) => {
-  if (/^cut$|^copy$/.test(menuItem.role) && !selection) {
+const filterCutCopy = (selection: string, menuItem: MenuItemConstructorOptions) => {
+  if (/^cut$|^copy$/.test(menuItem.role!) && !selection) {
     return;
   }
   return menuItem;
 };
 
-export default (createWindow, selection) => {
+export default (
+  createWindow: (fn?: (win: BrowserWindow) => void, options?: Record<string, any>) => BrowserWindow,
+  selection: string
+) => {
   const commandKeys = getCommandKeys(getDecoratedKeymaps());
-  const _shell = shellMenu(commandKeys, execCommand).submenu;
+  const _shell = shellMenu(commandKeys, execCommand).submenu as MenuItemConstructorOptions[];
   const _edit = editMenu(commandKeys, execCommand).submenu.filter(filterCutCopy.bind(null, selection));
   return _edit
     .concat(separator, _shell)
diff --git a/package.json b/package.json
index 5a6a867e..cb3db111 100644
--- a/package.json
+++ b/package.json
@@ -300,6 +300,8 @@
     "@types/color": "3.0.0",
     "@types/columnify": "^1.5.0",
     "@types/electron-devtools-installer": "2.2.0",
+    "@types/fs-extra": "8.0.1",
+    "@types/mkdirp": "0.5.2",
     "@types/mousetrap": "^1.6.3",
     "@types/node": "^12.12.21",
     "@types/pify": "3.0.2",
@@ -311,6 +313,7 @@
     "@types/styled-jsx": "2.2.8",
     "@types/uuid": "3.4.6",
     "@types/webdriverio": "^4.8.0",
+    "@types/winreg": "1.2.30",
     "@typescript-eslint/eslint-plugin": "2.11.0",
     "@typescript-eslint/parser": "2.12.0",
     "ava": "2.4.0",
diff --git a/yarn.lock b/yarn.lock
index d15c554b..f4b238ab 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -650,6 +650,13 @@
   resolved "https://registry.yarnpkg.com/@types/events/-/events-3.0.0.tgz#2862f3f58a9a7f7c3e78d79f130dd4d71c25c2a7"
   integrity sha512-EaObqwIvayI5a8dCzhFrjKzVwKLxjoG9T6Ppd5CEo07LRKfQ8Yokw54r5+Wq7FaBQ+yXRvQAYPrHwya1/UFt9g==
 
+"@types/fs-extra@8.0.1":
+  version "8.0.1"
+  resolved "https://registry.yarnpkg.com/@types/fs-extra/-/fs-extra-8.0.1.tgz#a2378d6e7e8afea1564e44aafa2e207dadf77686"
+  integrity sha512-J00cVDALmi/hJOYsunyT52Hva5TnJeKP5yd1r+mH/ZU0mbYZflR0Z5kw5kITtKTRYMhm1JMClOFYdHnQszEvqw==
+  dependencies:
+    "@types/node" "*"
+
 "@types/glob@^7.1.1":
   version "7.1.1"
   resolved "https://registry.yarnpkg.com/@types/glob/-/glob-7.1.1.tgz#aa59a1c6e3fbc421e07ccd31a944c30eba521575"
@@ -689,6 +696,13 @@
   resolved "https://registry.yarnpkg.com/@types/minimatch/-/minimatch-3.0.3.tgz#3dca0e3f33b200fc7d1139c0cd96c1268cadfd9d"
   integrity sha512-tHq6qdbT9U1IRSGf14CL0pUlULksvY9OZ+5eEgl1N7t+OA3tGvNpxJCzuKQlsNgCVwbAs670L1vcVQi8j9HjnA==
 
+"@types/mkdirp@0.5.2":
+  version "0.5.2"
+  resolved "https://registry.yarnpkg.com/@types/mkdirp/-/mkdirp-0.5.2.tgz#503aacfe5cc2703d5484326b1b27efa67a339c1f"
+  integrity sha512-U5icWpv7YnZYGsN4/cmh3WD2onMY0aJIiTE6+51TwJCttdHvtCYmkBNOobHlXwrJRL0nkH9jH4kD+1FAdMN4Tg==
+  dependencies:
+    "@types/node" "*"
+
 "@types/mousetrap@^1.6.3":
   version "1.6.3"
   resolved "https://registry.yarnpkg.com/@types/mousetrap/-/mousetrap-1.6.3.tgz#3159a01a2b21c9155a3d8f85588885d725dc987d"
@@ -780,6 +794,11 @@
   dependencies:
     "@types/node" "*"
 
+"@types/winreg@1.2.30":
+  version "1.2.30"
+  resolved "https://registry.yarnpkg.com/@types/winreg/-/winreg-1.2.30.tgz#91d6710e536d345b9c9b017c574cf6a8da64c518"
+  integrity sha1-kdZxDlNtNFucmwF8V0z2qNpkxRg=
+
 "@typescript-eslint/eslint-plugin@2.11.0":
   version "2.11.0"
   resolved "https://registry.yarnpkg.com/@typescript-eslint/eslint-plugin/-/eslint-plugin-2.11.0.tgz#4477c33491ccf0a9a3f4a30ef84978fa0ea0cad2"