diff --git a/build/controllers/AppController.php b/build/controllers/AppController.php
index a113483f4d..1af0398fd0 100644
--- a/build/controllers/AppController.php
+++ b/build/controllers/AppController.php
@@ -8,9 +8,7 @@
 namespace yii\build\controllers;
 
 use Yii;
-use yii\base\InvalidParamException;
 use yii\console\Controller;
-use yii\helpers\Console;
 use yii\helpers\FileHelper;
 
 /**
@@ -77,6 +75,12 @@ class AppController extends Controller
         $this->stdout("done.\n");
     }
 
+    /**
+     * Finds linkable applications
+     *
+     * @param string $dir directory to search in
+     * @return array list of applications command can link
+     */
     protected function findDirs($dir)
     {
         $list = [];
diff --git a/extensions/apidoc/helpers/ApiIndexer.php b/extensions/apidoc/helpers/ApiIndexer.php
index 8cb71c4a0b..cab957b21f 100644
--- a/extensions/apidoc/helpers/ApiIndexer.php
+++ b/extensions/apidoc/helpers/ApiIndexer.php
@@ -11,7 +11,6 @@ namespace yii\apidoc\helpers;
 use cebe\jssearch\Indexer;
 use cebe\jssearch\tokenizer\StandardTokenizer;
 use cebe\jssearch\TokenizerInterface;
-use yii\helpers\StringHelper;
 
 class ApiIndexer extends Indexer
 {
diff --git a/extensions/apidoc/helpers/ApiMarkdown.php b/extensions/apidoc/helpers/ApiMarkdown.php
index 7ce383635c..57a22c627c 100644
--- a/extensions/apidoc/helpers/ApiMarkdown.php
+++ b/extensions/apidoc/helpers/ApiMarkdown.php
@@ -9,7 +9,6 @@ namespace yii\apidoc\helpers;
 
 use cebe\markdown\GithubMarkdown;
 use phpDocumentor\Reflection\DocBlock\Type\Collection;
-use yii\apidoc\models\MethodDoc;
 use yii\apidoc\models\TypeDoc;
 use yii\apidoc\renderers\BaseRenderer;
 use yii\helpers\Inflector;
diff --git a/extensions/apidoc/helpers/ApiMarkdownTrait.php b/extensions/apidoc/helpers/ApiMarkdownTrait.php
index d2e0825adc..d6bbee0a83 100644
--- a/extensions/apidoc/helpers/ApiMarkdownTrait.php
+++ b/extensions/apidoc/helpers/ApiMarkdownTrait.php
@@ -8,7 +8,6 @@
 
 namespace yii\apidoc\helpers;
 
-use cebe\markdown\GithubMarkdown;
 use phpDocumentor\Reflection\DocBlock\Type\Collection;
 use yii\apidoc\models\MethodDoc;
 use yii\apidoc\models\TypeDoc;
diff --git a/extensions/apidoc/templates/pdf/GuideRenderer.php b/extensions/apidoc/templates/pdf/GuideRenderer.php
index e34f77552c..5b1fba4046 100644
--- a/extensions/apidoc/templates/pdf/GuideRenderer.php
+++ b/extensions/apidoc/templates/pdf/GuideRenderer.php
@@ -9,11 +9,9 @@ namespace yii\apidoc\templates\pdf;
 
 use cebe\markdown\latex\GithubMarkdown;
 use Yii;
-use yii\apidoc\helpers\ApiIndexer;
 use yii\apidoc\helpers\ApiMarkdownLaTeX;
 use yii\apidoc\helpers\IndexFileAnalyzer;
 use yii\helpers\Console;
-use yii\helpers\FileHelper;
 
 /**
  *
diff --git a/extensions/elasticsearch/ActiveQuery.php b/extensions/elasticsearch/ActiveQuery.php
index 499ecccb63..94fa0afbdb 100644
--- a/extensions/elasticsearch/ActiveQuery.php
+++ b/extensions/elasticsearch/ActiveQuery.php
@@ -7,7 +7,6 @@
 
 namespace yii\elasticsearch;
 
-use yii\base\NotSupportedException;
 use yii\db\ActiveQueryInterface;
 use yii\db\ActiveQueryTrait;
 use yii\db\ActiveRelationTrait;
diff --git a/framework/console/controllers/AssetController.php b/framework/console/controllers/AssetController.php
index cdb989c383..3ff88a4f0c 100644
--- a/framework/console/controllers/AssetController.php
+++ b/framework/console/controllers/AssetController.php
@@ -10,7 +10,6 @@ namespace yii\console\controllers;
 use Yii;
 use yii\console\Exception;
 use yii\console\Controller;
-use yii\helpers\StringHelper;
 use yii\helpers\VarDumper;
 
 /**
diff --git a/framework/helpers/BaseVarDumper.php b/framework/helpers/BaseVarDumper.php
index 364121dda5..882fa4e510 100644
--- a/framework/helpers/BaseVarDumper.php
+++ b/framework/helpers/BaseVarDumper.php
@@ -7,8 +7,6 @@
 
 namespace yii\helpers;
 
-use yii\base\Arrayable;
-
 /**
  * BaseVarDumper provides concrete implementation for [[VarDumper]].
  *
diff --git a/framework/rest/CreateAction.php b/framework/rest/CreateAction.php
index 2530627b52..1f7ae91d13 100644
--- a/framework/rest/CreateAction.php
+++ b/framework/rest/CreateAction.php
@@ -9,7 +9,6 @@ namespace yii\rest;
 
 use Yii;
 use yii\base\Model;
-use yii\db\ActiveRecord;
 use yii\helpers\Url;
 
 /**
diff --git a/framework/rest/DeleteAction.php b/framework/rest/DeleteAction.php
index 6c05acc6d1..98e3c5a753 100644
--- a/framework/rest/DeleteAction.php
+++ b/framework/rest/DeleteAction.php
@@ -8,7 +8,6 @@
 namespace yii\rest;
 
 use Yii;
-use yii\db\ActiveRecord;
 
 /**
  * DeleteAction implements the API endpoint for deleting a model.
diff --git a/tests/unit/framework/helpers/VarDumperTest.php b/tests/unit/framework/helpers/VarDumperTest.php
index 52467db140..443ef99e1c 100644
--- a/tests/unit/framework/helpers/VarDumperTest.php
+++ b/tests/unit/framework/helpers/VarDumperTest.php
@@ -1,7 +1,6 @@
 <?php
 namespace yiiunit\framework\helpers;
 
-use yii\data\ArrayDataProvider;
 use yii\helpers\VarDumper;
 use yiiunit\TestCase;
 
diff --git a/tests/unit/framework/rbac/DbManagerTestCase.php b/tests/unit/framework/rbac/DbManagerTestCase.php
index 150ed7c09c..f8795d7f86 100644
--- a/tests/unit/framework/rbac/DbManagerTestCase.php
+++ b/tests/unit/framework/rbac/DbManagerTestCase.php
@@ -4,7 +4,6 @@ namespace yiiunit\framework\rbac;
 use Yii;
 use yii\console\Application;
 use yii\console\Controller;
-use yii\console\controllers\MigrateController;
 use yii\db\Connection;
 use yii\rbac\DbManager;