diff --git a/packages/@vue/cli-service/package.json b/packages/@vue/cli-service/package.json
index 92a144846a..430cc20969 100644
--- a/packages/@vue/cli-service/package.json
+++ b/packages/@vue/cli-service/package.json
@@ -26,6 +26,9 @@
     "@intervolga/optimize-cssnano-plugin": "^1.0.5",
     "@soda/friendly-errors-webpack-plugin": "^1.7.1",
     "@soda/get-current-script": "^1.0.0",
+    "@types/minimist": "^1.2.0",
+    "@types/webpack": "^4.0.0",
+    "@types/webpack-dev-server": "^3.11.0",
     "@vue/cli-overlay": "^4.4.6",
     "@vue/cli-plugin-router": "^4.4.6",
     "@vue/cli-plugin-vuex": "^4.4.6",
diff --git a/packages/@vue/cli-service/types/ProjectOptions.d.ts b/packages/@vue/cli-service/types/ProjectOptions.d.ts
index df7daa2ddf..b4c0269e75 100644
--- a/packages/@vue/cli-service/types/ProjectOptions.d.ts
+++ b/packages/@vue/cli-service/types/ProjectOptions.d.ts
@@ -1,5 +1,5 @@
-import ChainableWebpackConfig from 'webpack-chain'
-import { WebpackOptions } from 'webpack/declarations/WebpackOptions'
+import ChainableWebpackConfig = require('webpack-chain')
+import { Configuration as WebpackOptions } from 'webpack'
 
 type PageEntry = string | string[];
 
@@ -29,7 +29,7 @@ interface CSSOptions {
   loaderOptions?: LoaderOptions;
 }
 
-export interface ProjectOptions {
+interface ProjectOptions {
   publicPath?: string;
   outputDir?: string;
   assetsDir?: string;
@@ -57,4 +57,6 @@ export interface ProjectOptions {
   pluginOptions?: object;
 }
 
-export type ConfigFunction = () => ProjectOptions
+type ConfigFunction = () => ProjectOptions
+
+export { ProjectOptions, ConfigFunction }
diff --git a/packages/@vue/cli-service/types/cli-service-test.ts b/packages/@vue/cli-service/types/cli-service-test.ts
new file mode 100644
index 0000000000..2f0a1b47a2
--- /dev/null
+++ b/packages/@vue/cli-service/types/cli-service-test.ts
@@ -0,0 +1,64 @@
+import { ServicePlugin } from '@vue/cli-service'
+
+const servicePlugin: ServicePlugin = (api, options) => {
+  const version = api.version
+  api.assertVersion(4)
+  api.assertVersion('^100')
+  api.getCwd()
+  api.resolve('src/main.js')
+  api.hasPlugin('eslint')
+  api.registerCommand(
+    'lint',
+    {
+      description: 'lint and fix source files',
+      usage: 'vue-cli-service lint [options] [...files]',
+      options: {
+        '--format [formatter]': 'specify formatter (default: codeframe)'
+      },
+      details: 'For more options, see https://eslint.org/docs/user-guide/command-line-interface#options'
+    },
+    args => {
+      require('./lint')(args, api)
+    }
+  )
+  api.registerCommand('lint', args => {})
+
+  api.chainWebpack(webpackConfig => {
+    if (process.env.NODE_ENV !== 'production' && process.env.NODE_ENV !== 'test') {
+      webpackConfig.devtool('cheap-module-eval-source-map')
+
+      webpackConfig.plugin('hmr').use(require('webpack/lib/HotModuleReplacementPlugin'))
+
+      webpackConfig.output.globalObject(`(typeof self !== 'undefined' ? self : this)`)
+    }
+  })
+
+  api.configureWebpack(config => {
+    config.output = {
+      path: 'test-dist-2'
+    }
+  })
+
+  api.configureWebpack(config => {
+    return {
+      devtool: config.devtool || 'source-map'
+    }
+  })
+
+  api.resolveWebpackConfig()
+
+  api.resolveWebpackConfig(api.resolveChainableWebpackConfig())
+
+  const { cacheIdentifier, cacheDirectory } = api.genCacheConfig(
+    'babel-loader',
+    {
+      '@babel/core': require('@babel/core/package.json').version,
+      '@vue/babel-preset-app': require('@vue/babel-preset-app/package.json').version,
+      'babel-loader': require('babel-loader/package.json').version,
+      modern: !!process.env.VUE_CLI_MODERN_BUILD,
+      browserslist: api.service.pkg.browserslist
+    },
+    ['babel.config.js', '.browserslistrc']
+  )
+}
+export = servicePlugin
diff --git a/packages/@vue/cli-service/types/index.d.ts b/packages/@vue/cli-service/types/index.d.ts
index d91403bdf8..dfb5e7f2d7 100644
--- a/packages/@vue/cli-service/types/index.d.ts
+++ b/packages/@vue/cli-service/types/index.d.ts
@@ -1 +1,137 @@
-export { ProjectOptions, ConfigFunction } from './ProjectOptions'
+import minimist = require('minimist')
+import ChainableConfig = require('webpack-chain')
+import webpack = require('webpack')
+import WebpackDevServer = require('webpack-dev-server')
+import express = require('express') // @types/webpack-dev-server depends on @types/express
+import { ProjectOptions } from './ProjectOptions'
+
+type RegisterCommandFn = (args: minimist.ParsedArgs, rawArgv: string[]) => any
+
+type RegisterCommandOpts = Partial<{
+  description: string
+  usage: string
+  options: {
+    [flags: string]: string
+  }
+  details: string
+}>
+
+type WebpackChainFn = (chainableConfig: ChainableConfig) => void
+
+type webpackRawConfigFn = ((config: webpack.Configuration) => webpack.Configuration | void) | webpack.Configuration
+
+type DevServerConfigFn = (app: express.Application, server: WebpackDevServer) => void
+
+interface CacheConfig {
+  cacheDirectory: string
+  cacheIdentifier: string
+}
+declare class PluginAPI {
+  id: string
+
+  service: any
+
+  readonly version: string
+
+  assertVersion(range: number | string): void
+
+  /**
+   * Current working directory.
+   */
+  getCwd(): string
+
+  /**
+   * Resolve path for a project.
+   *
+   * @param  _path - Relative path from project root
+   * @return The resolved absolute path.
+   */
+  resolve(_path: string): string
+
+  /**
+   * Check if the project has a given plugin.
+   *
+   * @param id - Plugin id, can omit the (@vue/|vue-|@scope/vue)-cli-plugin- prefix
+   * @return `boolean`
+   */
+  hasPlugin(id: string): boolean
+
+  /**
+   * Register a command that will become available as `vue-cli-service [name]`.
+   *
+   * @param name
+   * @param  [opts]
+   * @param  fn
+   */
+  registerCommand(name: string, fn: RegisterCommandFn): void
+  registerCommand(name: string, opts: RegisterCommandOpts, fn: RegisterCommandFn): void
+
+  /**
+   * Register a function that will receive a chainable webpack config
+   * the function is lazy and won't be called until `resolveWebpackConfig` is
+   * called
+   *
+   * @param fn
+   */
+  chainWebpack(fn: WebpackChainFn): void
+
+  /**
+   * Register
+   * - a webpack configuration object that will be merged into the config
+   * OR
+   * - a function that will receive the raw webpack config.
+   *   the function can either mutate the config directly or return an object
+   *   that will be merged into the config.
+   *
+   * @param fn
+   */
+  configureWebpack(fn: webpackRawConfigFn): void
+
+  /**
+   * Register a dev serve config function. It will receive the express `app`
+   * instance of the dev server.
+   *
+   * @param fn
+   */
+  configureDevServer(fn: DevServerConfigFn): void
+
+  /**
+   * Resolve the final raw webpack config, that will be passed to webpack.
+   *
+   * @param [chainableConfig]
+   * @return Raw webpack config.
+   */
+  resolveWebpackConfig(chainableConfig?: ChainableConfig): webpack.Configuration
+
+  /**
+   * Resolve an intermediate chainable webpack config instance, which can be
+   * further tweaked before generating the final raw webpack config.
+   * You can call this multiple times to generate different branches of the
+   * base webpack config.
+   * See https://github.com/mozilla-neutrino/webpack-chain
+   *
+   * @return ChainableWebpackConfig
+   */
+  resolveChainableWebpackConfig(): ChainableConfig
+
+  /**
+   * Generate a cache identifier from a number of variables
+   */
+  genCacheConfig(id: string, partialIdentifier: any, configFiles?: string | string[]): CacheConfig
+}
+
+/**
+ * Service plugin serves for modifying webpack config,
+ * creating new vue-cli service commands or changing existing commands
+ *
+ * @param api - A PluginAPI instance
+ * @param options - An object containing project local options specified in vue.config.js,
+ *    or in the "vue" field in package.json.
+ */
+type ServicePlugin = (
+  api: PluginAPI,
+  options: ProjectOptions
+) => any
+
+export { ProjectOptions, ServicePlugin, PluginAPI }
+export { ConfigFunction } from './ProjectOptions'
diff --git a/packages/@vue/cli-service/types/tsconfig.json b/packages/@vue/cli-service/types/tsconfig.json
new file mode 100644
index 0000000000..06338ace90
--- /dev/null
+++ b/packages/@vue/cli-service/types/tsconfig.json
@@ -0,0 +1,22 @@
+{
+  "files": [
+    "cli-service-test.ts",
+    "index.d.ts",
+    "ProjectOptions.d.ts"
+  ],
+  "compilerOptions": {
+    "module": "commonjs",
+    "lib": [
+      "es6"
+    ],
+    "noImplicitAny": true,
+    "noImplicitThis": true,
+    "strictNullChecks": true,
+    "esModuleInterop": true,
+    "strictFunctionTypes": true,
+    "types": [],
+    "noEmit": true,
+    "forceConsistentCasingInFileNames": true,
+    "baseUrl": "."
+  }
+}
diff --git a/packages/@vue/cli-test-utils/assertPromptModule.d.ts b/packages/@vue/cli-test-utils/assertPromptModule.d.ts
new file mode 100644
index 0000000000..2671ded9e5
--- /dev/null
+++ b/packages/@vue/cli-test-utils/assertPromptModule.d.ts
@@ -0,0 +1,16 @@
+import { PromptModuleAPI } from '@vue/cli'
+
+interface CliPromptModule {
+  (api: PromptModuleAPI): void
+}
+
+declare function assertPromptModule(
+  module: CliPromptModule | CliPromptModule[],
+  expectedPrompts: object[],
+  expectedOptions: object,
+  opts?: {
+    pluginsOnly?: boolean
+  },
+): Promise<void>
+
+export = assertPromptModule
diff --git a/packages/@vue/cli-test-utils/createJSONServer.d.ts b/packages/@vue/cli-test-utils/createJSONServer.d.ts
new file mode 100644
index 0000000000..723b3a506b
--- /dev/null
+++ b/packages/@vue/cli-test-utils/createJSONServer.d.ts
@@ -0,0 +1,21 @@
+import { Application } from 'express'
+
+declare function createJSONServer(
+  /**
+   * Either a path to a json file (e.g. 'db.json') or an object in memory
+   *
+   * Default:
+   *{
+   *  'posts': [
+   *    { 'id': 1, 'title': 'json-server', 'author': 'typicode' }
+   *  ],
+   *  'comments': [
+   *    { 'id': 1, 'body': 'some comment', 'postId': 1 }
+   *  ],
+   *  'profile': { 'name': 'typicode' }
+   *}
+   */
+  data?: string | object,
+): Application
+
+export = createJSONServer
diff --git a/packages/@vue/cli-test-utils/createServer.d.ts b/packages/@vue/cli-test-utils/createServer.d.ts
new file mode 100644
index 0000000000..45b1c50c78
--- /dev/null
+++ b/packages/@vue/cli-test-utils/createServer.d.ts
@@ -0,0 +1,11 @@
+/// <reference types="node" />
+import * as http from 'http'
+
+declare function createServer(options: {
+  /**
+   * Set a sub directory to be served
+   */
+  root: string
+}): http.Server
+
+export = createServer
diff --git a/packages/@vue/cli-test-utils/createTestProject.d.ts b/packages/@vue/cli-test-utils/createTestProject.d.ts
new file mode 100644
index 0000000000..a8564329d7
--- /dev/null
+++ b/packages/@vue/cli-test-utils/createTestProject.d.ts
@@ -0,0 +1,46 @@
+import execa = require('execa') // execa@1.0.0 needs @types/execa
+import { Preset } from '@vue/cli'
+
+/**
+ * create project at path `cwd`
+ */
+declare function createTestProject(
+  /**
+   * project name
+   */
+  name: string,
+  /**
+   * manual preset used to generate project.
+   *
+   * Example:
+   * {
+   *  plugins: {
+   *     '@vue/cli-plugin-babel': {}
+   *  }
+   * }
+   */
+  preset: Preset,
+  /** `path.resolve(cwd, name)` will be the project's root directory */
+  cwd?: string | null,
+  /**
+   * if init git repo
+   *
+   * Default:`true`
+   */
+  initGit?: boolean,
+): Promise<{
+  /** test project's root path */
+  dir: string
+  /** test if project contains the file */
+  has: (file: string) => boolean
+  /** read the content for the file */
+  read: (file: string) => Promise<string>
+  /** write file to project */
+  write: (file: string, content: any) => Promise<void>
+  /** execa command at root path of project  */
+  run: (command: string, args?: ReadonlyArray<string>) => execa.ExecaChildProcess
+  /** delete the file of project */
+  rm: (file: string) => Promise<void>
+}>
+
+export = createTestProject
diff --git a/packages/@vue/cli-test-utils/generateWithPlugin.d.ts b/packages/@vue/cli-test-utils/generateWithPlugin.d.ts
new file mode 100644
index 0000000000..6998c9c5a4
--- /dev/null
+++ b/packages/@vue/cli-test-utils/generateWithPlugin.d.ts
@@ -0,0 +1,32 @@
+import { GeneratorAPI, Preset } from '@vue/cli'
+
+type ApplyFn = (
+  api: GeneratorAPI,
+  options: any,
+  rootOptions: Preset,
+  invoking: boolean,
+) => any
+interface Plugin {
+  /** package name from plugin */
+  id: string
+  /** generator function from plugin */
+  apply: ApplyFn
+  /** parameter passed to generator function */
+  options?: any
+}
+
+/**
+ * invoke generator function, and generate file tree in memory
+ */
+declare function generateWithPlugin(
+  plugin: Plugin | Plugin[],
+): Promise<{
+  /** package.json Object */
+  pkg: Record<string, any>
+  /** virtual file tree, file path is the key of Object */
+  files: {
+    [filePath: string]: string | Buffer
+  }
+}>
+
+export = generateWithPlugin
diff --git a/packages/@vue/cli-test-utils/launchPuppeteer.d.ts b/packages/@vue/cli-test-utils/launchPuppeteer.d.ts
new file mode 100644
index 0000000000..1cb8383b56
--- /dev/null
+++ b/packages/@vue/cli-test-utils/launchPuppeteer.d.ts
@@ -0,0 +1,12 @@
+import { Browser, Page } from 'puppeteer'
+
+declare function launchPuppeteer(
+  url: string,
+): Promise<{
+  browser: Browser
+  page: Page
+  logs: string[]
+  requestUrls: string[]
+}>
+
+export = launchPuppeteer
diff --git a/packages/@vue/cli-test-utils/package.json b/packages/@vue/cli-test-utils/package.json
index e56cc57eb6..e6815b0dab 100644
--- a/packages/@vue/cli-test-utils/package.json
+++ b/packages/@vue/cli-test-utils/package.json
@@ -22,6 +22,11 @@
     "access": "public"
   },
   "dependencies": {
+    "@types/execa": "^0.9.0",
+    "@types/express": "4.17.4",
+    "@types/node": "*",
+    "@types/puppeteer": "^1.11.0",
+    "@vue/cli": "^4.3.0",
     "execa": "^1.0.0",
     "fs-extra": "^7.0.1",
     "json-server": "^0.15.0",
diff --git a/packages/@vue/cli-test-utils/serveWithPuppeteer.d.ts b/packages/@vue/cli-test-utils/serveWithPuppeteer.d.ts
new file mode 100644
index 0000000000..a18af5e6ee
--- /dev/null
+++ b/packages/@vue/cli-test-utils/serveWithPuppeteer.d.ts
@@ -0,0 +1,31 @@
+import execa = require('execa')
+import { Browser, Page } from 'puppeteer'
+
+interface Helpers {
+  getText: (selector: string) => Promise<string>
+  hasElement: (selector: string) => Promise<boolean>
+  hasClass: (selector: string, cls: string) => Promise<boolean>
+}
+
+interface Utils {
+  url: string
+  browser: Browser
+  page: Page
+  /** wait for hot replacement */
+  nextUpdate: () => Promise<string>
+  helpers: Helpers
+  requestUrls: string[]
+}
+
+declare function serveWithPuppeteer(
+  serve: () => execa.ExecaChildProcess,
+  /** Function which executes test codes*/
+  test: (arg: Utils) => any,
+  /**
+   * don't launch puppeteer.
+   * Defaults to `false`.
+   */
+  noPuppeteer?: boolean,
+): Promise<void>
+
+export = serveWithPuppeteer
diff --git a/packages/@vue/cli-test-utils/types/cli-test-utils-test.ts b/packages/@vue/cli-test-utils/types/cli-test-utils-test.ts
new file mode 100644
index 0000000000..7ce15e862b
--- /dev/null
+++ b/packages/@vue/cli-test-utils/types/cli-test-utils-test.ts
@@ -0,0 +1,106 @@
+import assertPromptModule from '@vue/cli-test-utils/assertPromptModule'
+import createJSONServer from '@vue/cli-test-utils/createJSONServer'
+import createServer from '@vue/cli-test-utils/createServer'
+import createTestProject from '@vue/cli-test-utils/createTestProject'
+import generateWithPlugin from '@vue/cli-test-utils/generateWithPlugin'
+import launchPuppeteer from '@vue/cli-test-utils/launchPuppeteer'
+import serveWithPuppeteer from '@vue/cli-test-utils/serveWithPuppeteer'
+import path from 'path'
+
+const expectedPrompts = [{ choose: 0 }]
+
+const expectedOptions = {
+  useConfigFiles: false,
+  plugins: {
+    foo: {}
+  }
+}
+
+assertPromptModule(
+  api => {
+    api.injectFeature({
+      name: 'Foo',
+      value: 'foo'
+    })
+    api.injectFeature({
+      name: 'Bar',
+      value: 'bar'
+    })
+    api.onPromptComplete((answers, options) => {
+      if (answers.features.includes('foo')) {
+        options.plugins.foo = {}
+      }
+    })
+  },
+  expectedPrompts,
+  expectedOptions
+)
+
+const mockServer1 = createJSONServer({
+  posts: [{ id: 1, title: 'server-one', author: 'typicode' }]
+}).listen(3000, () => {})
+
+const server = createServer({ root: path.resolve(__dirname, 'temp') })
+
+async function createTest() {
+  const project = await createTestProject(
+    'eslint',
+    {
+      plugins: {
+        '@vue/cli-plugin-babel': {},
+        '@vue/cli-plugin-eslint': {
+          config: 'airbnb',
+          lintOn: 'commit'
+        }
+      }
+    },
+    null,
+    true
+  )
+  const { dir, has, read, write, run, rm } = project
+
+  if (!has('src/main.js')) return
+
+  const main = await read('src/main.js')
+
+  const updatedMain = main.replace(/;/g, '')
+
+  await write('src/main.js', updatedMain)
+
+  await project.rm(`src/test.js`)
+
+  const { stdout } = await run('vue-cli-service lint')
+
+  await serveWithPuppeteer(
+    () => project.run('vue-cli-service serve'),
+    async ({ url, browser, page, nextUpdate, helpers, requestUrls }) => {
+      await helpers.getText('h1')
+    }
+  )
+}
+
+async function testGenerate() {
+  const { pkg, files } = await generateWithPlugin({
+    id: 'test-plugin',
+    apply: (api, options, rootOptions, invoking) => {
+      if (options.skip) return
+      console.log(rootOptions.bare, rootOptions.projectName, rootOptions.useConfigFiles, rootOptions.cssPreprocessor)
+      if (rootOptions.plugins) console.log(rootOptions.plugins['@vue/cli-service'])
+      if (rootOptions.configs) console.log(rootOptions.configs.vue)
+    },
+    options: {
+      skip: true
+    }
+  })
+  const lint = pkg.scripts.lint
+  const main = files['src/main.js']
+
+  await generateWithPlugin({
+    id: 'test-plugin-no-options',
+    apply: (api, options, rootOptions, invoking) => {}
+  })
+}
+
+async function testLaunchPuppeteer() {
+  const { browser, page, logs, requestUrls } = await launchPuppeteer(`http://localhost:8080/`)
+}
diff --git a/packages/@vue/cli-test-utils/types/tsconfig.json b/packages/@vue/cli-test-utils/types/tsconfig.json
new file mode 100644
index 0000000000..7b031c212c
--- /dev/null
+++ b/packages/@vue/cli-test-utils/types/tsconfig.json
@@ -0,0 +1,21 @@
+{
+  "files": [
+    "cli-test-utils-test.ts"
+  ],
+  "compilerOptions": {
+    "module": "commonjs",
+    "lib": [
+      "es6",
+      "dom"
+    ],
+    "noImplicitAny": true,
+    "noImplicitThis": true,
+    "strictNullChecks": true,
+    "esModuleInterop": true,
+    "strictFunctionTypes": true,
+    "types": [],
+    "noEmit": true,
+    "forceConsistentCasingInFileNames": true,
+    "baseUrl": "."
+  }
+}
diff --git a/packages/@vue/cli/package.json b/packages/@vue/cli/package.json
index 78b2c1a759..2c62a41659 100644
--- a/packages/@vue/cli/package.json
+++ b/packages/@vue/cli/package.json
@@ -5,6 +5,7 @@
   "bin": {
     "vue": "bin/vue.js"
   },
+  "types": "types/index.d.ts",
   "repository": {
     "type": "git",
     "url": "git+https://github.com/vuejs/vue-cli.git",
@@ -24,6 +25,8 @@
     "access": "public"
   },
   "dependencies": {
+    "@types/ejs": "^2.7.0",
+    "@types/inquirer": "^6.5.0",
     "@vue/cli-shared-utils": "^4.4.6",
     "@vue/cli-ui": "^4.4.6",
     "@vue/cli-ui-addon-webpack": "^4.4.6",
diff --git a/packages/@vue/cli/types/cli-test.ts b/packages/@vue/cli/types/cli-test.ts
new file mode 100644
index 0000000000..c9294c23b6
--- /dev/null
+++ b/packages/@vue/cli/types/cli-test.ts
@@ -0,0 +1,188 @@
+import { GeneratorPlugin, PromptModuleAPI } from '@vue/cli'
+
+const testPromptAPI = (cli: PromptModuleAPI) => {
+  cli.injectFeature({
+    name: 'Babel',
+    value: 'babel',
+    short: 'Babel',
+    // descriptions: 'Transpile modern JavaScript to older versions (for compatibility)',
+    // link: 'https://babeljs.io/',
+    checked: true
+  })
+
+  cli.injectOptionForPrompt('customBar', {
+    name: 'barChoice',
+    value: 'barChoice'
+  })
+  cli.onPromptComplete<{ features: string[]; useTsWithBabel: boolean }>((answers, options) => {
+    if (answers.features.includes('ts')) {
+      if (!answers.useTsWithBabel) {
+        return
+      }
+    } else if (!answers.features.includes('babel')) {
+      return
+    }
+    options.plugins['@vue/cli-plugin-babel'] = {}
+  })
+
+  cli.injectFeature({
+    name: 'CSS Pre-processors',
+    value: 'css-preprocessor'
+    // description: 'Add support for CSS pre-processors like Sass, Less or Stylus',
+    // link: 'https://cli.vuejs.org/guide/css.html'
+  })
+
+  const notice = 'PostCSS, Autoprefixer and CSS Modules are supported by default'
+  cli.injectPrompt<{ features: string[] }>({
+    name: 'cssPreprocessor',
+    when: answers => answers.features.includes('css-preprocessor'),
+    type: 'list',
+    message: `Pick a CSS pre-processor${process.env.VUE_CLI_API_MODE ? '' : ` (${notice})`}:`,
+    // description: `${notice}.`,
+    choices: [
+      {
+        name: 'Sass/SCSS (with dart-sass)',
+        value: 'dart-sass'
+      },
+      {
+        name: 'Sass/SCSS (with node-sass)',
+        value: 'node-sass'
+      },
+      {
+        name: 'Less',
+        value: 'less'
+      },
+      {
+        name: 'Stylus',
+        value: 'stylus'
+      }
+    ]
+  })
+}
+
+const generator: GeneratorPlugin = (api, options, rootOptions, invoking) => {
+  const version = api.cliVersion
+  const cliServiceVersion = api.cliServiceVersion
+  api.assertCliServiceVersion(4)
+  api.assertCliServiceVersion('^100')
+  api.hasPlugin('eslint')
+  api.hasPlugin('eslint', '^6.0.0')
+
+  api.addConfigTransform('fooConfig', {
+    file: {
+      json: ['foo.config.json']
+    }
+  })
+
+  api.extendPackage({
+    fooConfig: {
+      bar: 42
+    },
+    dependencies: {
+      'vue-router-layout': '^0.1.2'
+    }
+  })
+  api.extendPackage(() => ({
+    fooConfig: {
+      bar: 42
+    },
+    dependencies: {
+      'vue-router-layout': '^0.1.2'
+    }
+  }))
+  api.extendPackage(pkg => ({
+    foo: pkg.foo + 1
+  }))
+  api.extendPackage(
+    {
+      fooConfig: {
+        bar: 42
+      },
+      dependencies: {
+        'vue-router-layout': '^0.1.2'
+      }
+    },
+    true
+  )
+  api.extendPackage(
+    {
+      fooConfig: {
+        bar: 42
+      },
+      dependencies: {
+        'vue-router-layout': '^0.1.2'
+      }
+    },
+    {
+      merge: true,
+      prune: true,
+      warnIncompatibleVersions: true
+    }
+  )
+
+  api.render('./template')
+
+  api.render(
+    './template',
+    {
+      hasTS: api.hasPlugin('typescript'),
+      hasESLint: api.hasPlugin('eslint')
+    },
+    {
+      strict: true,
+      rmWhitespace: false
+    }
+  )
+
+  api.render((files, render) => {
+    files['foo2.js'] = render('foo(<%- n %>)', { n: 3 })
+    files['bar/bar2.js'] = render('bar(<%- n %>)', { n: 3 }, { rmWhitespace: false })
+  })
+
+  api.postProcessFiles(files => {
+    delete files['src/test.js']
+  })
+
+  api.onCreateComplete(() => {
+    console.log('complete')
+  })
+
+  api.afterInvoke(() => {
+    console.log('after invoke')
+  })
+
+  api.afterAnyInvoke(() => {
+    console.log('after any invoke')
+  })
+
+  api.exitLog('msg')
+  api.exitLog('msg', 'error')
+  api.genJSConfig({ foo: 1 })
+
+  api.extendPackage({
+    vue: {
+      publicPath: api.makeJSOnlyValue(`process.env.VUE_CONTEXT`)
+    }
+  })
+  api.transformScript(
+    'src/test.js',
+    (fileInfo, api, { additionalData }) => {
+      const j = api.jscodeshift
+      const root = j(fileInfo.source)
+      return root.toSource()
+    },
+    {
+      additionalData: []
+    }
+  )
+
+  api.injectImports('main.js', `import bar from 'bar'`)
+
+  api.injectRootOptions('main.js', ['foo', 'bar'])
+
+  api.resolve(api.entryFile)
+
+  const isInvoking = api.invoking
+}
+
+export = generator
diff --git a/packages/@vue/cli/types/index.d.ts b/packages/@vue/cli/types/index.d.ts
new file mode 100644
index 0000000000..6b4cf5deca
--- /dev/null
+++ b/packages/@vue/cli/types/index.d.ts
@@ -0,0 +1,243 @@
+import { DistinctQuestion, CheckboxChoiceOptions, Answers, ChoiceOptions } from 'inquirer'
+import { Parser, Transform } from 'jscodeshift'
+import * as ejs from 'ejs'
+
+interface RenderFile {
+  [path: string]: string | Buffer
+}
+
+type FileMiddleware = (files: RenderFile, render: typeof ejs.render) => void
+type PostProcessFilesCallback = (files: RenderFile) => void
+
+type RenderSource = string | RenderFile
+
+type TransformModule = Transform & {
+  default?: Transform
+  parser?: string | Parser
+}
+interface TransformOptions {
+  [prop: string]: any
+  parser?: string | Parser
+}
+interface __expressionFn {
+  (): void
+  __expression: string
+}
+
+interface OnPromptCompleteCb<T> {
+  (
+    answers: T,
+    options: {
+      useConfigFiles: boolean
+      plugins: Record<string, any>
+    }
+  ): void
+}
+type ExtendPackageOptions =
+  | {
+      prune?: boolean
+      merge?: boolean
+      warnIncompatibleVersions?: boolean
+    }
+  | boolean
+
+type Preset = Partial<{
+  [props: string]: any
+  bare: boolean
+  projectName: string
+  useConfigFiles: boolean
+  plugins: Record<string, any>
+  configs: Record<string, any>
+  cssPreprocessor: 'sass' | 'dart-sass' | 'node-sass' | 'less' | 'stylus'
+}>
+
+declare class PromptModuleAPI {
+  /** inject checkbox choice for feature prompt. */
+  injectFeature<T = Answers>(feature: CheckboxChoiceOptions<T>): void
+
+  injectPrompt<T = Answers>(prompt: DistinctQuestion<T>): void
+
+  injectOptionForPrompt(name: string, option: ChoiceOptions): void
+
+  /** run cb registered by prompt modules to finalize the preset. */
+  onPromptComplete<T = Answers>(cb: OnPromptCompleteCb<T>): void
+}
+
+declare class GeneratorAPI {
+  /**
+   * Resolve path for a project.
+   *
+   * @param  _paths - A sequence of relative paths or path segments
+   * @return The resolved absolute path, calculated based on the current project root.
+   */
+  resolve(..._paths: string[]): string
+
+  readonly cliVersion: string
+
+  assertCliVersion(range: number | string): void
+
+  readonly cliServiceVersion: string
+
+  assertCliServiceVersion(range: number | string): void
+
+  /**
+   * Check if the project has a given plugin.
+   *
+   * @param id - Plugin id, can omit the (@vue/|vue-|@scope/vue)-cli-plugin- prefix
+   * @param version - Plugin version. Defaults to ''
+   * @return `boolean`
+   */
+  hasPlugin(id: string, version?: string): boolean
+
+  /**
+   * Configure how config files are extracted.
+   *
+   * @param  key - Config key in package.json
+   * @param  options - Options
+   * @param  options.file - File descriptor
+   * Used to search for existing file.
+   * Each key is a file type (possible values: ['js', 'json', 'yaml', 'lines']).
+   * The value is a list of filenames.
+   * Example:
+   * {
+   *   js: ['.eslintrc.js'],
+   *   json: ['.eslintrc.json', '.eslintrc']
+   * }
+   * By default, the first filename will be used to create the config file.
+   */
+  addConfigTransform(key: string, options: { file: { [type: string]: string[] } }): void
+
+  /**
+   * Extend the package.json of the project.
+   * Also resolves dependency conflicts between plugins.
+   * Tool configuration fields may be extracted into standalone files before
+   * files are written to disk.
+   *
+   * @param fields - Fields to merge.
+   * @param [options] - Options for extending / merging fields.
+   * @param [options.prune=false] - Remove null or undefined fields
+   *    from the object after merging.
+   * @param [options.merge=true] deep-merge nested fields, note
+   *    that dependency fields are always deep merged regardless of this option.
+   * @param [options.warnIncompatibleVersions=true] Output warning
+   *    if two dependency version ranges don't intersect.
+   */
+  extendPackage(
+    fields: (pkg: Record<string, any>) => object,
+    options?: ExtendPackageOptions
+  ): void
+  extendPackage<T extends object>(
+    fields: T extends Function ? never : T,
+    options?: ExtendPackageOptions
+  ): void
+
+  /**
+   * Render template files into the virtual files tree object.
+   *
+   * @param source -
+   *   Can be one of:
+   *   - relative path to a directory;
+   *   - Object hash of { sourceTemplate: targetFile } mappings;
+   *   - a custom file middleware function.
+   * @param [additionalData] - additional data available to templates.
+   * @param [ejsOptions] - options for ejs.
+   */
+  render(source: RenderSource, additionalData?: object, ejsOptions?: ejs.Options): void
+  render(source: FileMiddleware): void
+
+  /**
+   * Push a file middleware that will be applied after all normal file
+   * middlewares have been applied.
+   *
+   * @param cb
+   */
+  postProcessFiles(cb: PostProcessFilesCallback): void
+
+  /**
+   * Push a callback to be called when the files have been written to disk.
+   *
+   * @param cb
+   */
+  onCreateComplete(cb: (...args: any[]) => any): void
+
+  /**
+   * same to `onCreateComplete`.
+   *
+   * @param cb
+   */
+  afterInvoke(cb: (...args: any[]) => any): void
+
+  /**
+   * Push a callback to be called when the files have been written to disk
+   * from non invoked plugins
+   *
+   * @param cb
+   */
+  afterAnyInvoke(cb: (...args: any[]) => any): void
+
+  /**
+   * Add a message to be printed when the generator exits (after any other standard messages).
+   *
+   * @param msg String or value to print after the generation is completed
+   * @param [type='log'] Type of message
+   */
+  exitLog(msg: any, type?: 'log' | 'info' | 'done' | 'warn' | 'error'): void
+
+  /**
+   * convenience method for generating a js config file from json
+   */
+  genJSConfig(value: any): string
+
+  /**
+   * Turns a string expression into executable JS for JS configs.
+   * @param str JS expression as a string
+   */
+  makeJSOnlyValue(str: string): __expressionFn
+
+  /**
+   * Run codemod on a script file or the script part of a .vue file
+   * @param file the path to the file to transform
+   * @param codemod the codemod module to run
+   * @param options additional options for the codemod
+   */
+  transformScript(file: string, codemod: TransformModule, options?: TransformOptions): void
+
+  /**
+   * Add import statements to a file.
+   */
+  injectImports(file: string, imports: string | string[]): void
+
+  /**
+   * Add options to the root Vue instance (detected by `new Vue`).
+   */
+  injectRootOptions(file: string, options: string | string[]): void
+
+  /**
+   * Get the entry file taking into account typescript.
+   *
+   */
+  readonly entryFile: 'src/main.ts' | 'src/main.js'
+
+  /**
+   * Is the plugin being invoked?
+   *
+   */
+  readonly invoking: boolean
+}
+
+/**
+ * function exported by a generator
+ * @param api - A GeneratorAPI instance
+ * @param options - These options are resolved during the prompt phase of project creation,
+ *    or loaded from a saved preset in ~/.vuerc
+ * @param rootOptions - The entire preset will be passed
+ * @param invoking - Is the plugin being invoked
+ */
+type GeneratorPlugin = (
+  api: GeneratorAPI,
+  options: any,
+  rootOptions: Preset,
+  invoking: boolean
+) => any
+
+export { PromptModuleAPI, GeneratorAPI, Preset, GeneratorPlugin }
diff --git a/packages/@vue/cli/types/tsconfig.json b/packages/@vue/cli/types/tsconfig.json
new file mode 100644
index 0000000000..d64e4de3b9
--- /dev/null
+++ b/packages/@vue/cli/types/tsconfig.json
@@ -0,0 +1,21 @@
+{
+  "files": [
+    "cli-test.ts",
+    "index.d.ts"
+  ],
+  "compilerOptions": {
+    "module": "commonjs",
+    "lib": [
+      "es6"
+    ],
+    "noImplicitAny": true,
+    "noImplicitThis": true,
+    "strictNullChecks": true,
+    "esModuleInterop": true,
+    "strictFunctionTypes": true,
+    "types": [],
+    "noEmit": true,
+    "forceConsistentCasingInFileNames": true,
+    "baseUrl": "."
+  }
+}
diff --git a/yarn.lock b/yarn.lock
index 66ce21cee7..6cc215c748 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3302,6 +3302,14 @@
   resolved "https://registry.yarnpkg.com/@types/color-name/-/color-name-1.1.1.tgz#1c1261bbeaa10a8055bbc5d8ab84b7b2afc846a0"
   integrity sha512-rr+OQyAjxze7GgWrSaJwydHStIhHq2lvY3BOC2Mj7KnzI7XK0Uw1TOOdI9lDoajEbSWLiYgoo4f1R51erQfhPQ==
 
+"@types/connect-history-api-fallback@*":
+  version "1.3.3"
+  resolved "https://registry.yarnpkg.com/@types/connect-history-api-fallback/-/connect-history-api-fallback-1.3.3.tgz#4772b79b8b53185f0f4c9deab09236baf76ee3b4"
+  integrity sha512-7SxFCd+FLlxCfwVwbyPxbR4khL9aNikJhrorw8nUIOqeuooc9gifBuDQOJw5kzN7i6i3vLn9G8Wde/4QDihpYw==
+  dependencies:
+    "@types/express-serve-static-core" "*"
+    "@types/node" "*"
+
 "@types/connect@*":
   version "3.4.33"
   resolved "https://registry.yarnpkg.com/@types/connect/-/connect-3.4.33.tgz#31610c901eca573b8713c3330abc6e6b9f588546"
@@ -3326,6 +3334,11 @@
   dependencies:
     "@types/express" "*"
 
+"@types/ejs@^2.7.0":
+  version "2.7.0"
+  resolved "https://registry.yarnpkg.com/@types/ejs/-/ejs-2.7.0.tgz#bc84e083eae38f64a287a6dab9012bbe1d96e295"
+  integrity sha512-kM2g9Fdk/du24fKuuQhA/LBleFR4Z4JP2MVKpLxQQSzofF1uJ06D+c05zfLDAkkDO55aEeNwJih0gHrE/Ci20A==
+
 "@types/eslint-visitor-keys@^1.0.0":
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/@types/eslint-visitor-keys/-/eslint-visitor-keys-1.0.0.tgz#1ee30d79544ca84d68d4b3cdb0af4f205663dd2d"
@@ -3336,6 +3349,13 @@
   resolved "https://registry.yarnpkg.com/@types/events/-/events-3.0.0.tgz#2862f3f58a9a7f7c3e78d79f130dd4d71c25c2a7"
   integrity sha512-EaObqwIvayI5a8dCzhFrjKzVwKLxjoG9T6Ppd5CEo07LRKfQ8Yokw54r5+Wq7FaBQ+yXRvQAYPrHwya1/UFt9g==
 
+"@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/express-serve-static-core@*":
   version "4.17.2"
   resolved "https://registry.yarnpkg.com/@types/express-serve-static-core/-/express-serve-static-core-4.17.2.tgz#f6f41fa35d42e79dbf6610eccbb2637e6008a0cf"
@@ -3394,6 +3414,30 @@
   resolved "https://registry.yarnpkg.com/@types/http-assert/-/http-assert-1.5.1.tgz#d775e93630c2469c2f980fc27e3143240335db3b"
   integrity sha512-PGAK759pxyfXE78NbKxyfRcWYA/KwW17X290cNev/qAsn9eQIxkH4shoNBafH37wewhDG/0p1cHPbK6+SzZjWQ==
 
+"@types/http-proxy-middleware@*":
+  version "0.19.3"
+  resolved "https://registry.yarnpkg.com/@types/http-proxy-middleware/-/http-proxy-middleware-0.19.3.tgz#b2eb96fbc0f9ac7250b5d9c4c53aade049497d03"
+  integrity sha512-lnBTx6HCOUeIJMLbI/LaL5EmdKLhczJY5oeXZpX/cXE4rRqb3RmV7VcMpiEfYkmTjipv3h7IAyIINe4plEv7cA==
+  dependencies:
+    "@types/connect" "*"
+    "@types/http-proxy" "*"
+    "@types/node" "*"
+
+"@types/http-proxy@*":
+  version "1.17.4"
+  resolved "https://registry.yarnpkg.com/@types/http-proxy/-/http-proxy-1.17.4.tgz#e7c92e3dbe3e13aa799440ff42e6d3a17a9d045b"
+  integrity sha512-IrSHl2u6AWXduUaDLqYpt45tLVCtYv7o4Z0s1KghBCDgIIS9oW5K1H8mZG/A2CfeLdEa7rTd1ACOiHBc1EMT2Q==
+  dependencies:
+    "@types/node" "*"
+
+"@types/inquirer@^6.5.0":
+  version "6.5.0"
+  resolved "https://registry.yarnpkg.com/@types/inquirer/-/inquirer-6.5.0.tgz#b83b0bf30b88b8be7246d40e51d32fe9d10e09be"
+  integrity sha512-rjaYQ9b9y/VFGOpqBEXRavc3jh0a+e6evAbI31tMda8VlPaSy0AZJfXsvmIe3wklc7W6C3zCSfleuMXR7NOyXw==
+  dependencies:
+    "@types/through" "*"
+    rxjs "^6.4.0"
+
 "@types/istanbul-lib-coverage@*", "@types/istanbul-lib-coverage@^2.0.0":
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/@types/istanbul-lib-coverage/-/istanbul-lib-coverage-2.0.1.tgz#42995b446db9a48a11a07ec083499a860e9138ff"
@@ -3480,6 +3524,11 @@
   resolved "https://registry.yarnpkg.com/@types/minimatch/-/minimatch-3.0.3.tgz#3dca0e3f33b200fc7d1139c0cd96c1268cadfd9d"
   integrity sha512-tHq6qdbT9U1IRSGf14CL0pUlULksvY9OZ+5eEgl1N7t+OA3tGvNpxJCzuKQlsNgCVwbAs670L1vcVQi8j9HjnA==
 
+"@types/minimist@^1.2.0":
+  version "1.2.0"
+  resolved "https://registry.yarnpkg.com/@types/minimist/-/minimist-1.2.0.tgz#69a23a3ad29caf0097f06eda59b361ee2f0639f6"
+  integrity sha1-aaI6OtKcrwCX8G7aWbNh7i8GOfY=
+
 "@types/mocha@^5.2.6":
   version "5.2.7"
   resolved "https://registry.yarnpkg.com/@types/mocha/-/mocha-5.2.7.tgz#315d570ccb56c53452ff8638738df60726d5b6ea"
@@ -3507,6 +3556,13 @@
   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/puppeteer@^1.11.0":
+  version "1.20.4"
+  resolved "https://registry.yarnpkg.com/@types/puppeteer/-/puppeteer-1.20.4.tgz#30cb0a4ee5394c420119cbdf9f079d6595a07f67"
+  integrity sha512-T/kFgyLnYWk0H94hxI0HbOLnqHvzBRpfS0F0oo9ESGI24oiC2fEjDcMbBjuK3wH7VLsaIsp740vVXVzR1dsMNg==
+  dependencies:
+    "@types/node" "*"
+
 "@types/q@^1.5.1":
   version "1.5.2"
   resolved "https://registry.yarnpkg.com/@types/q/-/q-1.5.2.tgz#690a1475b84f2a884fd07cd797c00f5f31356ea8"
@@ -3560,6 +3616,13 @@
   resolved "https://registry.yarnpkg.com/@types/tapable/-/tapable-1.0.5.tgz#9adbc12950582aa65ead76bffdf39fe0c27a3c02"
   integrity sha512-/gG2M/Imw7cQFp8PGvz/SwocNrmKFjFsm5Pb8HdbHkZ1K8pmuPzOX4VeVoiEecFCVf4CsN1r3/BRvx+6sNqwtQ==
 
+"@types/through@*":
+  version "0.0.30"
+  resolved "https://registry.yarnpkg.com/@types/through/-/through-0.0.30.tgz#e0e42ce77e897bd6aead6f6ea62aeb135b8a3895"
+  integrity sha512-FvnCJljyxhPM3gkRgWmxmDZyAQSiBQQWLI0A0VFL0K7W1oRUrPJSqNO0NvTnLkBcotdlp3lKvaT0JrnyRDkzOg==
+  dependencies:
+    "@types/node" "*"
+
 "@types/uglify-js@*":
   version "3.9.2"
   resolved "https://registry.yarnpkg.com/@types/uglify-js/-/uglify-js-3.9.2.tgz#01992579debba674e1e359cd6bcb1a1d0ab2e02b"
@@ -3567,24 +3630,35 @@
   dependencies:
     source-map "^0.6.1"
 
+"@types/webpack-dev-server@^3.11.0":
+  version "3.11.0"
+  resolved "https://registry.yarnpkg.com/@types/webpack-dev-server/-/webpack-dev-server-3.11.0.tgz#bcc3b85e7dc6ac2db25330610513f2228c2fcfb2"
+  integrity sha512-3+86AgSzl18n5P1iUP9/lz3G3GMztCp+wxdDvVuNhx1sr1jE79GpYfKHL8k+Vht3N74K2n98CuAEw4YPJCYtDA==
+  dependencies:
+    "@types/connect-history-api-fallback" "*"
+    "@types/express" "*"
+    "@types/http-proxy-middleware" "*"
+    "@types/serve-static" "*"
+    "@types/webpack" "*"
+
 "@types/webpack-env@^1.15.2":
   version "1.15.2"
   resolved "https://registry.yarnpkg.com/@types/webpack-env/-/webpack-env-1.15.2.tgz#927997342bb9f4a5185a86e6579a0a18afc33b0a"
   integrity sha512-67ZgZpAlhIICIdfQrB5fnDvaKFcDxpKibxznfYRVAT4mQE41Dido/3Ty+E3xGBmTogc5+0Qb8tWhna+5B8z1iQ==
 
 "@types/webpack-sources@*":
-  version "1.4.0"
-  resolved "https://registry.yarnpkg.com/@types/webpack-sources/-/webpack-sources-1.4.0.tgz#e58f1f05f87d39a5c64cf85705bdbdbb94d4d57e"
-  integrity sha512-c88dKrpSle9BtTqR6ifdaxu1Lvjsl3C5OsfvuUbUwdXymshv1TkufUAXBajCCUM/f/TmnkZC/Esb03MinzSiXQ==
+  version "0.1.7"
+  resolved "https://registry.yarnpkg.com/@types/webpack-sources/-/webpack-sources-0.1.7.tgz#0a330a9456113410c74a5d64180af0cbca007141"
+  integrity sha512-XyaHrJILjK1VHVC4aVlKsdNN5KBTwufMb43cQs+flGxtPAf/1Qwl8+Q0tp5BwEGaI8D6XT1L+9bSWXckgkjTLw==
   dependencies:
     "@types/node" "*"
     "@types/source-list-map" "*"
-    source-map "^0.7.3"
+    source-map "^0.6.1"
 
-"@types/webpack@*":
-  version "4.41.17"
-  resolved "https://registry.yarnpkg.com/@types/webpack/-/webpack-4.41.17.tgz#0a69005e644d657c85b7d6ec1c826a71bebd1c93"
-  integrity sha512-6FfeCidTSHozwKI67gIVQQ5Mp0g4X96c2IXxX75hYEQJwST/i6NyZexP//zzMOBb+wG9jJ7oO8fk9yObP2HWAw==
+"@types/webpack@*", "@types/webpack@^4.0.0":
+  version "4.41.10"
+  resolved "https://registry.yarnpkg.com/@types/webpack/-/webpack-4.41.10.tgz#2e1f6b3508a249854efe3dcc7690905ac5ee10be"
+  integrity sha512-vIy0qaq8AjOjZLuFPqpo7nAJzcoVXMdw3mvpNN07Uvdy0p1IpJeLNBe3obdRP7FX2jIusDE7z1pZa0A6qYUgnA==
   dependencies:
     "@types/anymatch" "*"
     "@types/node" "*"