diff --git a/.flowconfig b/.flowconfig
new file mode 100644
index 00000000..62f4cc32
--- /dev/null
+++ b/.flowconfig
@@ -0,0 +1,23 @@
+# https://flowtype.org/docs/advanced-configuration
+[include]
+
+[ignore]
+# Generate dirs.
+<PROJECT_ROOT>/__dist/.*
+<PROJECT_ROOT>/__obj/.*
+<PROJECT_ROOT>/__test_cache/.*
+
+#
+
+[libs]
+
+[options]
+module.system=node
+module.system.node.resolve_dirname=node_modules
+
+munge_underscores=true
+
+suppress_comment= \\(.\\|\n\\)*\\$FlowFixMe
+
+[version]
+^0.33.0
diff --git a/package.json b/package.json
index ab178419..ab944038 100644
--- a/package.json
+++ b/package.json
@@ -22,7 +22,8 @@
     "build_development": "cross-env NODE_ENV=development npm run build",
     "build": "gulp build",
     "test": "gulp test",
-    "gulp": "gulp"
+    "gulp": "gulp",
+    "flow": "flow"
   },
   "keywords": [
     "browser",
@@ -77,8 +78,11 @@
     "autoprefixer": "^6.5.0",
     "babel-cli": "^6.16.0",
     "babel-core": "^6.17.0",
+    "babel-eslint": "^7.0.0",
     "babel-loader": "^6.2.5",
+    "babel-plugin-syntax-flow": "^6.13.0",
     "babel-plugin-transform-es2015-modules-commonjs": "^6.16.0",
+    "babel-plugin-transform-flow-strip-types": "^6.14.0",
     "babel-plugin-transform-inline-environment-variables": "^6.8.0",
     "babel-plugin-transform-node-env-inline": "^6.8.0",
     "babel-plugin-transform-react-constant-elements": "^6.9.1",
@@ -92,6 +96,7 @@
     "eslint": "^3.7.0",
     "eslint-plugin-node": "^2.1.2",
     "eslint-plugin-react": "^6.3.0",
+    "flow-bin": "^0.33.0",
     "font-awesome": "^4.6.3",
     "glob": "^7.1.0",
     "gulp": "^3.9.1",
diff --git a/src/server/.eslintrc.js b/src/server/.eslintrc.js
index 046c9087..5d2d1f3b 100644
--- a/src/server/.eslintrc.js
+++ b/src/server/.eslintrc.js
@@ -29,13 +29,10 @@
 // ESLint Configuration Files enables to include comments.
 // http://eslint.org/docs/configuring/#comments-in-configuration-files
 module.exports = {
+    'parser': 'babel-eslint',
 
     'parserOptions': {
-        'ecmaVersion': 8,
         'sourceType': 'module',
-        'ecmaFeatures': {
-            'jsx': true
-        },
     },
 
     'settings': {
diff --git a/src/server/models/Hostmask.js b/src/server/models/Hostmask.js
index b34f6acb..daedfee8 100644
--- a/src/server/models/Hostmask.js
+++ b/src/server/models/Hostmask.js
@@ -23,13 +23,23 @@
  * THE SOFTWARE.
  */
 
+// @flow
+
+type Args = {
+    nick: string,
+    username: string,
+    hostname: string,
+    string: string,
+}
+
 export class Hostmask {
 
-    /**
-     *  @constructor
-     *  @param  {?} attr
-     */
-    constructor(attr) {
+    nick: string;
+    username: string;
+    hostname: string;
+    string: string;
+
+    constructor(attr: Args) {
         const data = Object.assign({
             nick: '',
             username: '',
diff --git a/tools/build/babelrc_for_server.js b/tools/build/babelrc_for_server.js
index 2dea9765..a2b731db 100644
--- a/tools/build/babelrc_for_server.js
+++ b/tools/build/babelrc_for_server.js
@@ -20,6 +20,10 @@ module.exports = {
         // for React
         'syntax-jsx',
         'transform-react-jsx',
+
+        // for flowtype
+        'plugin-syntax-flow',
+        'plugin-transform-flow-strip-types',
     ],
 
     'env': {