diff --git a/.eslintrc b/.eslintrc
index 0d854fc2c..7a74d6ef9 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -17,5 +17,10 @@
 		"no-console": 0,
 		"no-unused-vars": 0,
 		"no-empty": 0
+	},
+	"globals": {
+		"ENV": true,
+		"VERSION": true,
+		"API": true
 	}
 }
diff --git a/gulpfile.ts b/gulpfile.ts
index df7f7e329..b70e5d8bc 100644
--- a/gulpfile.ts
+++ b/gulpfile.ts
@@ -28,7 +28,7 @@ import config from './src/conf';
 
 const uglify = uglifyComposer(uglifyes, console);
 
-const env = process.env.NODE_ENV;
+const env = process.env.NODE_ENV || 'development';
 const isProduction = env === 'production';
 const isDebug = !isProduction;
 
@@ -123,6 +123,7 @@ gulp.task('build:client:script', () =>
 	gulp.src(['./src/web/app/boot.js', './src/web/app/safe.js'])
 		.pipe(replace('VERSION', JSON.stringify(version)))
 		.pipe(replace('API', JSON.stringify(config.api_url)))
+		.pipe(replace('ENV', JSON.stringify(env)))
 		.pipe(isProduction ? uglify({
 			toplevel: true
 		} as any) : gutil.noop())
diff --git a/src/web/app/boot.js b/src/web/app/boot.js
index 4b7d67942..2ee61745b 100644
--- a/src/web/app/boot.js
+++ b/src/web/app/boot.js
@@ -36,6 +36,7 @@
 	let lang = navigator.language.split('-')[0];
 	if (!/^(en|ja)$/.test(lang)) lang = 'en';
 	if (localStorage.getItem('lang')) lang = localStorage.getItem('lang');
+	if (ENV != 'production') lang = 'ja';
 
 	// Detect the user agent
 	const ua = navigator.userAgent.toLowerCase();
@@ -69,7 +70,8 @@
 	const isDebug = localStorage.getItem('debug') == 'true';
 
 	// Whether use raw version script
-	const raw = localStorage.getItem('useRawScript') == 'true' && isDebug;
+	const raw = (localStorage.getItem('useRawScript') == 'true' && isDebug)
+		|| ENV != 'production';
 
 	// Load an app script
 	// Note: 'async' make it possible to load the script asyncly.
diff --git a/webpack.config.ts b/webpack.config.ts
index 873251087..05ecd9677 100644
--- a/webpack.config.ts
+++ b/webpack.config.ts
@@ -21,7 +21,7 @@ import locales from './locales';
 const meta = require('./package.json');
 const version = meta.version;
 
-const env = process.env.NODE_ENV;
+const env = process.env.NODE_ENV || 'development';
 const isProduction = env === 'production';
 
 //#region Replacer definitions
@@ -42,11 +42,12 @@ global['base64replacement'] = (_, key) => {
 
 const langs = Object.keys(locales);
 
-let entries = langs.map(l => [l, false]);
-entries = entries.concat(langs.map(l => [l, true]));
+const entries = isProduction
+	? langs.map(l => [l, false]).concat(langs.map(l => [l, true]))
+	: [['ja', false]];
 
 module.exports = entries.map(x => {
-	const [lang, doMinify] = x;
+	const [lang, shouldOptimize] = x;
 
 	// Chunk name
 	const name = lang;
@@ -65,7 +66,7 @@ module.exports = entries.map(x => {
 
 	const output = {
 		path: __dirname + '/built/web/assets',
-		filename: `[name].${version}.${lang}.${doMinify ? 'min' : 'raw'}.js`
+		filename: `[name].${version}.${lang}.${shouldOptimize ? 'min' : 'raw'}.js`
 	};
 
 	const i18nReplacer = new I18nReplacer(lang as string);
@@ -106,9 +107,7 @@ module.exports = entries.map(x => {
 		}),
 		new webpack.DefinePlugin(_consts),
 		new webpack.DefinePlugin({
-			'process.env': {
-				NODE_ENV: JSON.stringify(process.env.NODE_ENV)
-			}
+			'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV)
 		}),
 		new WebpackOnBuildPlugin(stats => {
 			fs.writeFileSync('./version.json', JSON.stringify({
@@ -117,7 +116,7 @@ module.exports = entries.map(x => {
 		})
 	];
 
-	if (doMinify) {
+	if (shouldOptimize) {
 		plugins.push(new webpack.optimize.ModuleConcatenationPlugin());
 	}
 
@@ -243,10 +242,10 @@ module.exports = entries.map(x => {
 		cache: true,
 		devtool: false, //'source-map',
 		optimization: {
-			minimize: isProduction && doMinify
+			minimize: isProduction && shouldOptimize
 		},
 		mode: isProduction
-			? doMinify
+			? shouldOptimize
 				? 'production'
 				: 'development'
 			: 'development'