diff --git a/package.json b/package.json
index b246401b3..6354a418e 100644
--- a/package.json
+++ b/package.json
@@ -22,8 +22,7 @@
   },
   "scripts": {
     "build": "tsc -p tsconfig.json",
-    "test": "jest --config ./test/jest.config.json",
-    "prepare": "npm run build"
+    "test": "jest --config ./test/jest.config.json"
   },
   "files": [
     "dist",
@@ -67,9 +66,16 @@
     "typescript": "^3.4.5"
   },
   "devDependencies": {
+    "@types/ansi-escapes": "^4.0.0",
     "@types/camelcase": "^5.2.0",
+    "@types/execa": "^0.9.0",
     "@types/fs-extra": "^5.0.5",
+    "@types/mkdirp": "^0.5.2",
+    "@types/ms": "^0.7.30",
     "@types/node": "^11.13.8",
+    "@types/ora": "^3.2.0",
+    "@types/rollup-plugin-json": "^3.0.2",
+    "@types/rollup-plugin-sourcemaps": "^0.4.2",
     "husky": "^2.1.0",
     "prettier": "^1.17.0",
     "pretty-quick": "^1.10.0",
diff --git a/src/constants.js b/src/constants.js
deleted file mode 100644
index b9afb0fb5..000000000
--- a/src/constants.js
+++ /dev/null
@@ -1,17 +0,0 @@
-import fs from 'fs-extra';
-import path from 'path';
-import { resolveApp } from './utils';
-
-let paths = {};
-
-try {
-  paths = {
-    appPackageJson: resolveApp('package.json'),
-    testsSetup: resolveApp('test/setupTests.ts'),
-    appRoot: resolveApp('.'),
-    appSrc: resolveApp('src'),
-    appDist: resolveApp('dist'),
-  };
-} catch (e) {}
-
-export { paths };
diff --git a/src/constants.ts b/src/constants.ts
new file mode 100644
index 000000000..5dc28ca26
--- /dev/null
+++ b/src/constants.ts
@@ -0,0 +1,9 @@
+import { resolveApp } from './utils';
+
+export const paths = {
+  appPackageJson: resolveApp('package.json'),
+  testsSetup: resolveApp('test/setupTests.ts'),
+  appRoot: resolveApp('.'),
+  appSrc: resolveApp('src'),
+  appDist: resolveApp('dist'),
+};
diff --git a/src/createJestConfig.js b/src/createJestConfig.ts
similarity index 92%
rename from src/createJestConfig.js
rename to src/createJestConfig.ts
index 4948cdff2..5b518a77c 100644
--- a/src/createJestConfig.js
+++ b/src/createJestConfig.ts
@@ -1,5 +1,3 @@
-import { appPackageJson } from './constants';
-
 export function createJestConfig(resolve, rootDir) {
   return {
     transform: {
diff --git a/src/createRollupConfig.js b/src/createRollupConfig.ts
similarity index 97%
rename from src/createRollupConfig.js
rename to src/createRollupConfig.ts
index 1768ee8da..80e83eb7d 100644
--- a/src/createRollupConfig.js
+++ b/src/createRollupConfig.ts
@@ -5,7 +5,7 @@ import {
   removeScope,
   external,
 } from './utils';
-import { paths, appPackageJson } from './constants';
+import { paths } from './constants';
 import { sizeSnapshot } from 'rollup-plugin-size-snapshot';
 import { terser } from 'rollup-plugin-terser';
 import babel from 'rollup-plugin-babel';
@@ -79,7 +79,7 @@ export function createRollupConfig(format, env, opts) {
           'module',
           'main',
           opts.target !== 'node' ? 'browser' : undefined,
-        ].filter(Boolean),
+        ].filter(Boolean) as string[],
       }),
       format === 'umd' &&
         commonjs({
diff --git a/src/env.d.ts b/src/env.d.ts
new file mode 100644
index 000000000..1a1adff22
--- /dev/null
+++ b/src/env.d.ts
@@ -0,0 +1,12 @@
+declare module 'asyncro';
+declare module 'enquirer';
+declare module 'jpjs';
+declare module 'ora';
+declare module 'sade';
+declare module 'tiny-glob/sync';
+
+// Rollup plugins
+declare module '@jaredpalmer/rollup-plugin-preserve-shebang';
+declare module 'rollup-plugin-babel';
+declare module 'rollup-plugin-size-snapshot';
+declare module 'rollup-plugin-terser';
diff --git a/src/getInstallArgs.js b/src/getInstallArgs.js
deleted file mode 100644
index 110c1de04..000000000
--- a/src/getInstallArgs.js
+++ /dev/null
@@ -1,7 +0,0 @@
-export default function getInstallArgs(cmd, packages) {
-  if (cmd === 'npm') {
-    return ['install', ...packages, '--save-dev'];
-  } else if (cmd === 'yarn') {
-    return ['add', ...packages, '--dev'];
-  }
-}
diff --git a/src/getInstallArgs.ts b/src/getInstallArgs.ts
new file mode 100644
index 000000000..951347457
--- /dev/null
+++ b/src/getInstallArgs.ts
@@ -0,0 +1,10 @@
+import { InstallCmd } from './getInstallCmd';
+
+export default function getInstallArgs(cmd: InstallCmd, packages: string[]) {
+  switch (cmd) {
+    case 'npm':
+      return ['install', ...packages, '--save-dev'];
+    case 'yarn':
+      return ['add', ...packages, '--dev'];
+  }
+}
diff --git a/src/getInstallCmd.js b/src/getInstallCmd.ts
similarity index 61%
rename from src/getInstallCmd.js
rename to src/getInstallCmd.ts
index 70e255176..e215c590e 100644
--- a/src/getInstallCmd.js
+++ b/src/getInstallCmd.ts
@@ -1,8 +1,10 @@
 import execa from 'execa';
 
-let cmd;
+let cmd: InstallCmd;
 
-export default function getInstallCmd() {
+export type InstallCmd = 'yarn' | 'npm';
+
+export default function getInstallCmd(): InstallCmd {
   if (cmd) {
     return cmd;
   }
diff --git a/src/index.js b/src/index.ts
similarity index 96%
rename from src/index.js
rename to src/index.ts
index caf2298ae..56849c41e 100755
--- a/src/index.js
+++ b/src/index.ts
@@ -6,7 +6,7 @@ import { rollup, watch } from 'rollup';
 import asyncro from 'asyncro';
 import chalk from 'chalk';
 import util from 'util';
-import fs from 'fs-extra';
+import * as fs from 'fs-extra';
 import jest from 'jest';
 import logError from './logError';
 import path from 'path';
@@ -43,15 +43,15 @@ try {
   appPackageJson = fs.readJSONSync(resolveApp('package.json'));
 } catch (e) {}
 
-const stat = util.promisify(fs.stat);
-
 export const isDir = name =>
-  stat(name)
+  fs
+    .stat(name)
     .then(stats => stats.isDirectory())
     .catch(() => false);
 
 export const isFile = name =>
-  stat(name)
+  fs
+    .stat(name)
     .then(stats => stats.isFile())
     .catch(() => false);
 
@@ -66,8 +66,8 @@ async function jsOrTs(filename) {
 }
 
 async function getInputs(entries, source) {
-  let inputs = [];
-  let stub = [];
+  let inputs: any[] = [];
+  let stub: any[] = [];
   stub
     .concat(
       entries && entries.length
@@ -197,7 +197,7 @@ prog
     const installSpinner = ora(Messages.installing(deps)).start();
     try {
       const cmd = getInstallCmd();
-      await execa(cmd, getInstallArgs(getInstallCmd(), deps));
+      await execa(cmd, getInstallArgs(cmd, deps));
       installSpinner.succeed('Installed dependecines');
       console.log(Messages.start(pkg));
     } catch (error) {
@@ -237,10 +237,7 @@ prog
         module.exports = require('./${safeVariableName(
           opts.name
         )}.cjs.development.js')
-      }`,
-          {
-            overwrite: true,
-          }
+      }`
         );
       } catch (e) {}
     }
@@ -296,7 +293,7 @@ prog
     const [cjsDev, cjsProd, ...otherConfigs] = createBuildConfigs(opts);
     if (opts.format.includes('cjs')) {
       try {
-        await mkdirp(resolveApp('./dist'));
+        await util.promisify(mkdirp)(resolveApp('./dist'));
         const promise = fs
           .writeFile(
             resolveApp('./dist/index.js'),
@@ -311,10 +308,7 @@ prog
         module.exports = require('./${safePackageName(
           opts.name
         )}.cjs.development.js')
-      }`,
-            {
-              overwrite: true,
-            }
+      }`
           )
           .catch(e => logError(e));
         logger(promise, 'Creating entry file');
@@ -362,7 +356,9 @@ prog
       argv.push('--watchAll');
     }
 
-    const maybeTestSetupFiledExists = await fs.exists(paths.testsSetup);
+    const maybeTestSetupFiledExists = await (fs.exists as any)(
+      paths.testsSetup
+    );
     const setupTestsFile = maybeTestSetupFiledExists
       ? '<rootDir>/src/setupTests.ts'
       : undefined;
diff --git a/src/logError.js b/src/logError.ts
similarity index 100%
rename from src/logError.js
rename to src/logError.ts
diff --git a/src/messages.js b/src/messages.ts
similarity index 100%
rename from src/messages.js
rename to src/messages.ts
diff --git a/src/output.js b/src/output.ts
similarity index 89%
rename from src/output.js
rename to src/output.ts
index e3dcb1a08..5a0327682 100644
--- a/src/output.js
+++ b/src/output.ts
@@ -20,11 +20,6 @@ export const success = msg => {
   console.log(`${chalk.green('> Success!')} ${msg}`);
 };
 
-export const time = () => {
-  const start = new Date();
-  return chalk.gray(`[${ms(new Date() - start)}]`);
-};
-
 export const wait = msg => {
   const spinner = ora(chalk.green(msg));
   spinner.color = 'blue';
@@ -47,7 +42,7 @@ export const prompt = opts => {
       const s = v.toString();
 
       function cleanup() {
-        process.stdin.setRawMode(false);
+        process.stdin.setRawMode!(false);
         process.stdin.removeListener('data', ondata);
       }
 
@@ -64,7 +59,7 @@ export const prompt = opts => {
       }
     };
 
-    process.stdin.setRawMode(true);
+    process.stdin.setRawMode!(true);
     process.stdin.resume();
     process.stdin.on('data', ondata);
   });
diff --git a/src/utils.js b/src/utils.ts
similarity index 100%
rename from src/utils.js
rename to src/utils.ts
diff --git a/tsconfig.json b/tsconfig.json
index 10be04587..8cedd1ce0 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,4 +1,6 @@
 {
+  "include": ["src/**/*"],
+  "exclude": ["src/template/**/*"],
   "compilerOptions": {
     "allowJs": true,
     "importHelpers": true,
@@ -8,13 +10,8 @@
     "module": "commonjs",
     "rootDir": "src",
     "strict": true,
+    "noImplicitAny": false,
     "skipLibCheck": true,
-    "target": "es2017",
-  },
-  "include": [
-    "src/**/*"
-  ],
-  "exclude": [
-    "src/template/**/*"
-  ]
-}
\ No newline at end of file
+    "target": "es2017"
+  }
+}
diff --git a/yarn.lock b/yarn.lock
index e1235f49a..69c068e29 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -382,6 +382,13 @@
     "@types/istanbul-lib-coverage" "^2.0.0"
     "@types/yargs" "^12.0.9"
 
+"@types/ansi-escapes@^4.0.0":
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/@types/ansi-escapes/-/ansi-escapes-4.0.0.tgz#cf52d455628bc3fab95db971ab0f23c84778cc05"
+  integrity sha512-50x8OpY2c2UMDuiN7Uq1ITWngAiL3B8L9v6GU0J+IrndEypNfGJaZSgpuOBwhIu+7xwkhDj9OniK6z6MaeN7zQ==
+  dependencies:
+    ansi-escapes "*"
+
 "@types/babel__core@^7.1.0":
   version "7.1.1"
   resolved "https://registry.yarnpkg.com/@types/babel__core/-/babel__core-7.1.1.tgz#ce9a9e5d92b7031421e1d0d74ae59f572ba48be6"
@@ -427,6 +434,13 @@
   resolved "https://registry.yarnpkg.com/@types/estree/-/estree-0.0.39.tgz#e177e699ee1b8c22d23174caaa7422644389509f"
   integrity sha512-EYNwp3bU+98cpU4lAWYYL7Zz+2gryWH1qbdDTidVd6hkiR6weksdbMadyXKXNPEkQFhXM+hVO9ZygomHXp+AIw==
 
+"@types/execa@^0.9.0":
+  version "0.9.0"
+  resolved "https://registry.yarnpkg.com/@types/execa/-/execa-0.9.0.tgz#9b025d2755f17e80beaf9368c3f4f319d8b0fb93"
+  integrity sha512-mgfd93RhzjYBUHHV532turHC2j4l/qxsF/PbfDmprHDEUHmNZGlDn1CEsulGK3AfsPdhkWzZQT/S/k0UGhLGsA==
+  dependencies:
+    "@types/node" "*"
+
 "@types/fs-extra@^5.0.5":
   version "5.0.5"
   resolved "https://registry.yarnpkg.com/@types/fs-extra/-/fs-extra-5.0.5.tgz#080d90a792f3fa2c5559eb44bd8ef840aae9104b"
@@ -439,6 +453,18 @@
   resolved "https://registry.yarnpkg.com/@types/istanbul-lib-coverage/-/istanbul-lib-coverage-2.0.1.tgz#42995b446db9a48a11a07ec083499a860e9138ff"
   integrity sha512-hRJD2ahnnpLgsj6KWMYSrmXkM3rm2Dl1qkx6IOFD5FnuNPXJIG5L0dhgKXCYTRMGzU4n0wImQ/xfmRc4POUFlg==
 
+"@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/ms@^0.7.30":
+  version "0.7.30"
+  resolved "https://registry.yarnpkg.com/@types/ms/-/ms-0.7.30.tgz#f6c38b7ecbbf698b0bbd138315a0f0f18954f85f"
+  integrity sha512-OftRLCgAzJP7vmKn9by/GVjnf4hloz/pXNOwPo0vKGAfXI7GqWXJi9N2kRar4cP5s1dGwuwcagWqO6iHBTq1Mg==
+
 "@types/node@*":
   version "10.12.18"
   resolved "https://registry.yarnpkg.com/@types/node/-/node-10.12.18.tgz#1d3ca764718915584fcd9f6344621b7672665c67"
@@ -454,6 +480,13 @@
   resolved "https://registry.yarnpkg.com/@types/normalize-package-data/-/normalize-package-data-2.4.0.tgz#e486d0d97396d79beedd0a6e33f4534ff6b4973e"
   integrity sha512-f5j5b/Gf71L+dbqxIpQ4Z2WlmI/mPJ0fOkGGmFgtb6sAu97EPczzbS3/tJKxmcYDj55OX6ssqwDAWOHIYDRDGA==
 
+"@types/ora@^3.2.0":
+  version "3.2.0"
+  resolved "https://registry.yarnpkg.com/@types/ora/-/ora-3.2.0.tgz#b2f65d1283a8f36d8b0f9ee767e0732a2f429362"
+  integrity sha512-jll99xUKpiFbIFZSQcxm4numfsLaOWBzWNaRk3PvTSE7BPqTzzOCFmS0mQ7m8qkTfmYhuYbehTGsxkvRLPC++w==
+  dependencies:
+    ora "*"
+
 "@types/resolve@0.0.8":
   version "0.0.8"
   resolved "https://registry.yarnpkg.com/@types/resolve/-/resolve-0.0.8.tgz#f26074d238e02659e323ce1a13d041eee280e194"
@@ -461,6 +494,22 @@
   dependencies:
     "@types/node" "*"
 
+"@types/rollup-plugin-json@^3.0.2":
+  version "3.0.2"
+  resolved "https://registry.yarnpkg.com/@types/rollup-plugin-json/-/rollup-plugin-json-3.0.2.tgz#1153136a515ed4fbb7ef214ace496f5fc3ed7796"
+  integrity sha512-eTRym5nG4HEKDR/KrTnCMYwF7V0hgVjEesvtJCK3V8ho/aT0ZFRFgsDtx38VarM30HCsN372+i4FKYwnhcwiVA==
+  dependencies:
+    "@types/node" "*"
+    rollup "^0.63.4"
+
+"@types/rollup-plugin-sourcemaps@^0.4.2":
+  version "0.4.2"
+  resolved "https://registry.yarnpkg.com/@types/rollup-plugin-sourcemaps/-/rollup-plugin-sourcemaps-0.4.2.tgz#ce3752116834aeb8b798da77a180612fb6ff617a"
+  integrity sha512-dqF1rMFy4O8yNlQYwYPos5Cfav0f6M7PLH8B33gsslQ0zA9MX1jMGokwNuJ3Z3EXAzsKF/xAWNHpFmELcgYJww==
+  dependencies:
+    "@types/node" "*"
+    rollup "^0.63.4"
+
 "@types/stack-utils@^1.0.1":
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/@types/stack-utils/-/stack-utils-1.0.1.tgz#0a851d3bd96498fa25c33ab7278ed3bd65f06c3e"
@@ -695,6 +744,13 @@ ansi-colors@^3.2.1:
   resolved "https://registry.yarnpkg.com/ansi-colors/-/ansi-colors-3.2.4.tgz#e3a3da4bfbae6c86a9c285625de124a234026fbf"
   integrity sha512-hHUXGagefjN2iRrID63xckIvotOXOojhQKWIPUZ4mNUZ9nLZW+7FMNoE1lOkEhNWYsx/7ysGIuJYCiMAA9FnrA==
 
+ansi-escapes@*:
+  version "4.1.0"
+  resolved "https://registry.yarnpkg.com/ansi-escapes/-/ansi-escapes-4.1.0.tgz#62a9e5fa78e99c5bb588b1796855f5d729231b53"
+  integrity sha512-2VY/iCUZTDLD/qxptS3Zn3c6k2MeIbYqjRXqM8T5oC7N2mMjh3xIU3oYru6cHGbldFa9h5i8N0fP65UaUqrMWA==
+  dependencies:
+    type-fest "^0.3.0"
+
 ansi-escapes@^3.0.0, ansi-escapes@^3.1.0:
   version "3.1.0"
   resolved "https://registry.yarnpkg.com/ansi-escapes/-/ansi-escapes-3.1.0.tgz#f73207bb81207d75fd6c83f125af26eea378ca30"
@@ -1331,6 +1387,11 @@ cli-spinners@^1.1.0, cli-spinners@^1.3.1:
   resolved "https://registry.yarnpkg.com/cli-spinners/-/cli-spinners-1.3.1.tgz#002c1990912d0d59580c93bd36c056de99e4259a"
   integrity sha512-1QL4544moEsDVH9T/l6Cemov/37iv1RtoKf7NJ04A60+4MREXNfx/QvavbH6QoGdsD4N4Mwy49cmaINR/o2mdg==
 
+cli-spinners@^2.0.0:
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/cli-spinners/-/cli-spinners-2.1.0.tgz#22c34b4d51f573240885b201efda4e4ec9fff3c7"
+  integrity sha512-8B00fJOEh1HPrx4fo5eW16XmE1PcL1tGpGrxy63CXGP9nHdPBN63X75hA1zhvQuhVztJWLqV58Roj2qlNM7cAA==
+
 cliui@^4.0.0:
   version "4.1.0"
   resolved "https://registry.yarnpkg.com/cliui/-/cliui-4.1.0.tgz#348422dbe82d800b3022eef4f6ac10bf2e4d1b49"
@@ -4158,6 +4219,18 @@ optionator@^0.8.1:
     type-check "~0.3.2"
     wordwrap "~1.0.0"
 
+ora@*:
+  version "3.4.0"
+  resolved "https://registry.yarnpkg.com/ora/-/ora-3.4.0.tgz#bf0752491059a3ef3ed4c85097531de9fdbcd318"
+  integrity sha512-eNwHudNbO1folBP3JsZ19v9azXWtQZjICdr3Q0TDPIaeBQ3mXLrh54wM+er0+hSp+dWKf+Z8KM58CYzEyIYxYg==
+  dependencies:
+    chalk "^2.4.2"
+    cli-cursor "^2.1.0"
+    cli-spinners "^2.0.0"
+    log-symbols "^2.2.0"
+    strip-ansi "^5.2.0"
+    wcwidth "^1.0.1"
+
 ora@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/ora/-/ora-3.0.0.tgz#8179e3525b9aafd99242d63cc206fd64732741d0"
@@ -4975,6 +5048,14 @@ rollup-pluginutils@^2.5.0, rollup-pluginutils@^2.6.0:
     estree-walker "^0.6.0"
     micromatch "^3.1.10"
 
+rollup@^0.63.4:
+  version "0.63.5"
+  resolved "https://registry.yarnpkg.com/rollup/-/rollup-0.63.5.tgz#5543eecac9a1b83b7e1be598b5be84c9c0a089db"
+  integrity sha512-dFf8LpUNzIj3oE0vCvobX6rqOzHzLBoblyFp+3znPbjiSmSvOoK2kMKx+Fv9jYduG1rvcCfCveSgEaQHjWRF6g==
+  dependencies:
+    "@types/estree" "0.0.39"
+    "@types/node" "*"
+
 rollup@^1.10.1:
   version "1.10.1"
   resolved "https://registry.yarnpkg.com/rollup/-/rollup-1.10.1.tgz#aeb763bbe98f707dc6496708db88372fa66687e7"
@@ -5422,7 +5503,7 @@ strip-ansi@^4.0.0:
   dependencies:
     ansi-regex "^3.0.0"
 
-strip-ansi@^5.0.0:
+strip-ansi@^5.0.0, strip-ansi@^5.2.0:
   version "5.2.0"
   resolved "https://registry.yarnpkg.com/strip-ansi/-/strip-ansi-5.2.0.tgz#8c9a536feb6afc962bdfa5b104a5091c1ad9c0ae"
   integrity sha512-DuRs1gKbBqsMKIZlrffwlug8MHkcnpjs5VPmL1PAh+mA30U0DTotfDZ0d2UUsXpPmPmMMJ6W773MaA3J+lbiWA==
@@ -5718,6 +5799,11 @@ type-check@~0.3.2:
   dependencies:
     prelude-ls "~1.1.2"
 
+type-fest@^0.3.0:
+  version "0.3.1"
+  resolved "https://registry.yarnpkg.com/type-fest/-/type-fest-0.3.1.tgz#63d00d204e059474fe5e1b7c011112bbd1dc29e1"
+  integrity sha512-cUGJnCdr4STbePCgqNFbpVNCepa+kAVohJs1sLhxzdH+gnEoOd8VhbYa7pD3zZYGiURWM2xzEII3fQcRizDkYQ==
+
 type-fest@^0.4.1:
   version "0.4.1"
   resolved "https://registry.yarnpkg.com/type-fest/-/type-fest-0.4.1.tgz#8bdf77743385d8a4f13ba95f610f5ccd68c728f8"