diff --git a/api/components/ApiUser/Component.php b/api/components/ApiUser/Component.php
index 2c9e0c3..46acfc1 100644
--- a/api/components/ApiUser/Component.php
+++ b/api/components/ApiUser/Component.php
@@ -7,6 +7,7 @@ use yii\web\User as YiiUserComponent;
  * @property Identity|null $identity
  *
  * @method Identity|null getIdentity()
+ * @method Identity|null loginByAccessToken(string $token, $type = null)
  */
 class Component extends YiiUserComponent {
 
diff --git a/api/components/ErrorHandler.php b/api/components/ErrorHandler.php
index f8a1ac9..54e8531 100644
--- a/api/components/ErrorHandler.php
+++ b/api/components/ErrorHandler.php
@@ -2,11 +2,12 @@
 namespace api\components;
 
 use api\modules\authserver\exceptions\AuthserverException;
+use api\modules\session\exceptions\SessionServerException;
 
 class ErrorHandler extends \yii\web\ErrorHandler {
 
     public function convertExceptionToArray($exception) {
-        if ($exception instanceof AuthserverException) {
+        if ($exception instanceof AuthserverException || $exception instanceof SessionServerException) {
             return [
                 'error' => $exception->getName(),
                 'errorMessage' => $exception->getMessage(),
diff --git a/api/config/main.php b/api/config/main.php
index 35302cb..1bd152b 100644
--- a/api/config/main.php
+++ b/api/config/main.php
@@ -9,7 +9,7 @@ $params = array_merge(
 return [
     'id' => 'accounts-site-api',
     'basePath' => dirname(__DIR__),
-    'bootstrap' => ['log', 'authserver'],
+    'bootstrap' => ['log', 'authserver', 'sessionserver'],
     'controllerNamespace' => 'api\controllers',
     'params' => $params,
     'components' => [
@@ -56,5 +56,8 @@ return [
             'class' => \api\modules\authserver\Module::class,
             'baseDomain' => $params['authserverDomain'],
         ],
+        'sessionserver' => [
+            'class' => \api\modules\session\Module::class,
+        ],
     ],
 ];
diff --git a/api/modules/authserver/models/ValidateForm.php b/api/modules/authserver/models/ValidateForm.php
index ec279eb..e56ea48 100644
--- a/api/modules/authserver/models/ValidateForm.php
+++ b/api/modules/authserver/models/ValidateForm.php
@@ -24,7 +24,7 @@ class ValidateForm extends Form {
             throw new ForbiddenOperationException('Invalid token.');
         }
 
-        if (!$result->isActual()) {
+        if ($result->isExpired()) {
             $result->delete();
             throw new ForbiddenOperationException('Token expired.');
         }
diff --git a/api/modules/session/Module.php b/api/modules/session/Module.php
new file mode 100644
index 0000000..365ffb0
--- /dev/null
+++ b/api/modules/session/Module.php
@@ -0,0 +1,31 @@
+<?php
+namespace api\modules\session;
+
+use Yii;
+use yii\base\BootstrapInterface;
+
+class Module extends \yii\base\Module implements BootstrapInterface {
+
+    public $id = 'session';
+
+    public $defaultRoute = 'session';
+
+    /**
+     * @param \yii\base\Application $app the application currently running
+     */
+    public function bootstrap($app) {
+        $app->getUrlManager()->addRules([
+            // TODO: define normal routes
+            //$this->baseDomain . '/' . $this->id . '/auth/<action>' => $this->id . '/authentication/<action>',
+        ], false);
+    }
+
+    public static function info($message) {
+        Yii::info($message, 'session');
+    }
+
+    public static function error($message) {
+        Yii::info($message, 'session');
+    }
+
+}
diff --git a/api/modules/session/controllers/SessionController.php b/api/modules/session/controllers/SessionController.php
new file mode 100644
index 0000000..466a051
--- /dev/null
+++ b/api/modules/session/controllers/SessionController.php
@@ -0,0 +1,28 @@
+<?php
+namespace api\modules\session\controllers;
+
+use api\controllers\ApiController;
+use api\modules\session\models\JoinForm;
+
+class SessionController extends ApiController {
+
+    public function behaviors() {
+        $behaviors = parent::behaviors();
+        unset($behaviors['authenticator']);
+
+        return $behaviors;
+    }
+
+    public function actionJoin() {
+        $joinForm = new JoinForm();
+        $joinForm->loadByPost();
+        $joinForm->join();
+
+        return ['id' => 'OK'];
+    }
+
+    public function actionJoinLegacy() {
+
+    }
+
+}
diff --git a/api/modules/session/exceptions/ForbiddenOperationException.php b/api/modules/session/exceptions/ForbiddenOperationException.php
new file mode 100644
index 0000000..420aaec
--- /dev/null
+++ b/api/modules/session/exceptions/ForbiddenOperationException.php
@@ -0,0 +1,10 @@
+<?php
+namespace api\modules\session\exceptions;
+
+class ForbiddenOperationException extends SessionServerException  {
+
+    public function __construct($message, $code = 0, \Exception $previous = null) {
+        parent::__construct($status = 401, $message, $code, $previous);
+    }
+
+}
diff --git a/api/modules/session/exceptions/IllegalArgumentException.php b/api/modules/session/exceptions/IllegalArgumentException.php
new file mode 100644
index 0000000..2250a22
--- /dev/null
+++ b/api/modules/session/exceptions/IllegalArgumentException.php
@@ -0,0 +1,10 @@
+<?php
+namespace api\modules\session\exceptions;
+
+class IllegalArgumentException extends SessionServerException {
+
+    public function __construct($status = null, $message = null, $code = 0, \Exception $previous = null) {
+        parent::__construct(400, 'credentials can not be null.', $code, $previous);
+    }
+
+}
diff --git a/api/modules/session/exceptions/SessionServerException.php b/api/modules/session/exceptions/SessionServerException.php
new file mode 100644
index 0000000..98bb656
--- /dev/null
+++ b/api/modules/session/exceptions/SessionServerException.php
@@ -0,0 +1,19 @@
+<?php
+namespace api\modules\session\exceptions;
+
+use ReflectionClass;
+use yii\web\HttpException;
+
+class SessionServerException extends HttpException {
+
+    /**
+     * Рефлексия быстрее, как ни странно:
+     * @url https://coderwall.com/p/cpxxxw/php-get-class-name-without-namespace#comment_19313
+     *
+     * @return string
+     */
+    public function getName() {
+        return (new ReflectionClass($this))->getShortName();
+    }
+
+}
diff --git a/api/modules/session/models/Form.php b/api/modules/session/models/Form.php
new file mode 100644
index 0000000..bd4a383
--- /dev/null
+++ b/api/modules/session/models/Form.php
@@ -0,0 +1,27 @@
+<?php
+namespace api\modules\session\models;
+
+use Yii;
+use yii\base\Model;
+
+abstract class Form extends Model {
+
+    public function formName() {
+        return '';
+    }
+
+    public function loadByGet() {
+        return $this->load(Yii::$app->request->get());
+    }
+
+    public function loadByPost() {
+        $data = Yii::$app->request->post();
+        // TODO: проверить, парсит ли Yii2 raw body и что он делает, если там неспаршенный json
+        /*if (empty($data)) {
+            $data = $request->getJsonRawBody(true);
+        }*/
+
+        return $this->load($data);
+    }
+
+}
diff --git a/api/modules/session/models/JoinForm.php b/api/modules/session/models/JoinForm.php
new file mode 100644
index 0000000..dbd6d1a
--- /dev/null
+++ b/api/modules/session/models/JoinForm.php
@@ -0,0 +1,122 @@
+<?php
+namespace api\modules\session\models;
+
+use api\modules\session\exceptions\ForbiddenOperationException;
+use api\modules\session\exceptions\IllegalArgumentException;
+use api\modules\session\Module as Session;
+use api\modules\session\validators\RequiredValidator;
+use common\models\OauthScope as S;
+use common\validators\UuidValidator;
+use common\models\Account;
+use common\models\MinecraftAccessKey;
+use Yii;
+use yii\base\ErrorException;
+use yii\web\UnauthorizedHttpException;
+
+class JoinForm extends Form {
+
+    public $accessToken;
+    public $selectedProfile;
+    public $serverId;
+
+    private $account;
+
+    public function rules() {
+        return [
+            [['accessToken', 'selectedProfile', 'serverId'], RequiredValidator::class],
+            [['accessToken', 'selectedProfile'], 'validateUuid'],
+            [['accessToken'], 'validateAccessToken'],
+        ];
+    }
+
+    public function join() {
+        Session::info(
+            "User with access_token = '{$this->accessToken}' trying join to server with server_id = " .
+            "'{$this->serverId}'."
+        );
+        if (!$this->validate()) {
+            return false;
+        }
+
+        $account = $this->getAccount();
+        $sessionModel = new SessionModel($account->username, $this->serverId);
+        if (!$sessionModel->save()) {
+            throw new ErrorException('Cannot save join session model');
+        }
+
+        Session::info(
+            "User with access_token = '{$this->accessToken}' and nickname = '{$account->username}' successfully " .
+            "joined to server_id = '{$this->serverId}'."
+        );
+
+        return true;
+    }
+
+    public function validateUuid($attribute) {
+        if ($this->hasErrors($attribute)) {
+            return;
+        }
+
+        $validator = new UuidValidator();
+        $validator->validateAttribute($this, $attribute);
+
+        if ($this->hasErrors($attribute)) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    /**
+     * @throws \api\modules\session\exceptions\SessionServerException
+     */
+    public function validateAccessToken() {
+        $accessToken = $this->accessToken;
+        /** @var MinecraftAccessKey|null $accessModel */
+        $accessModel = MinecraftAccessKey::findOne($accessToken);
+        if ($accessModel === null) {
+            try {
+                $identity = Yii::$app->apiUser->loginByAccessToken($accessToken);
+            } catch (UnauthorizedHttpException $e) {
+                $identity = null;
+            }
+
+            if ($identity === null) {
+                Session::error("User with access_token = '{$accessToken}' failed join by wrong access_token.");
+                throw new ForbiddenOperationException('Invalid access_token.');
+            }
+
+            if (!Yii::$app->apiUser->can(S::MINECRAFT_SERVER_SESSION)) {
+                Session::error("User with access_token = '{$accessToken}' doesn't have enough scopes to make join.");
+                throw new ForbiddenOperationException('The token does not have required scope.');
+            }
+
+            $accessModel = $identity->getAccessToken();
+            $account = $identity->getAccount();
+        } else {
+            $account = $accessModel->account;
+        }
+
+        /** @var MinecraftAccessKey|\common\models\OauthAccessToken $accessModel */
+        if ($accessModel->isExpired()) {
+            Session::error("User with access_token = '{$accessToken}' failed join by expired access_token.");
+            throw new ForbiddenOperationException('Expired access_token.');
+        }
+
+        if ($account->uuid !== $this->selectedProfile) {
+            Session::error(
+                "User with access_token = '{$accessToken}' trying to join with identity = '{$this->selectedProfile}'," .
+                " but access_token issued to account with id = '{$account->uuid}'."
+            );
+            throw new ForbiddenOperationException('Wrong selected_profile.');
+        }
+
+        $this->account = $account;
+    }
+
+    /**
+     * @return Account|null
+     */
+    protected function getAccount() {
+        return $this->account;
+    }
+
+}
diff --git a/api/modules/session/models/SessionModel.php b/api/modules/session/models/SessionModel.php
new file mode 100644
index 0000000..1efd748
--- /dev/null
+++ b/api/modules/session/models/SessionModel.php
@@ -0,0 +1,57 @@
+<?php
+namespace api\modules\session\models;
+
+use Yii;
+
+class SessionModel {
+
+    const KEY_TIME = 120; // 2 min
+
+    public $username;
+
+    public $serverId;
+
+    public function __construct(string $username, string $serverId) {
+        $this->username = $username;
+        $this->serverId = $serverId;
+    }
+
+    /**
+     * @param $username
+     * @param $serverId
+     *
+     * @return static|null
+     */
+    public static function find($username, $serverId) {
+        $key = static::buildKey($username, $serverId);
+        $result = Yii::$app->redis->executeCommand('GET', [$key]);
+        if (!$result) {
+            /** @noinspection PhpIncompatibleReturnTypeInspection шторм что-то сума сходит, когда видит static */
+            return null;
+        }
+
+        $data = json_decode($result, true);
+        $model = new static($data['username'], $data['serverId']);
+
+        return $model;
+    }
+
+    public function save() {
+        $key = static::buildKey($this->username, $this->serverId);
+        $data = json_encode([
+            'username' => $this->username,
+            'serverId' => $this->serverId,
+        ]);
+
+        return Yii::$app->redis->executeCommand('SETEX', [$key, self::KEY_TIME, $data]);
+    }
+
+    public function delete() {
+        return Yii::$app->redis->executeCommand('DEL', [static::buildKey($this->username, $this->serverId)]);
+    }
+
+    protected static function buildKey($username, $serverId) {
+        return md5('minecraft:join-server:' . mb_strtolower($username) . ':' . $serverId);
+    }
+
+}
diff --git a/api/modules/session/validators/RequiredValidator.php b/api/modules/session/validators/RequiredValidator.php
new file mode 100644
index 0000000..63cae1f
--- /dev/null
+++ b/api/modules/session/validators/RequiredValidator.php
@@ -0,0 +1,25 @@
+<?php
+namespace api\modules\session\validators;
+
+use api\modules\session\exceptions\IllegalArgumentException;
+
+/**
+ * Для данного модуля нам не принципиально, что там за ошибка: если не хватает хотя бы одного
+ * параметра - тут же отправляем исключение и дело с концом
+ */
+class RequiredValidator extends \yii\validators\RequiredValidator {
+
+    /**
+     * @param string $value
+     * @return null
+     * @throws \api\modules\session\exceptions\SessionServerException
+     */
+    protected function validateValue($value) {
+        if (parent::validateValue($value) !== null) {
+            throw new IllegalArgumentException();
+        }
+
+        return null;
+    }
+
+}
diff --git a/common/models/MinecraftAccessKey.php b/common/models/MinecraftAccessKey.php
index 5df1712..d07ed5a 100644
--- a/common/models/MinecraftAccessKey.php
+++ b/common/models/MinecraftAccessKey.php
@@ -53,8 +53,8 @@ class MinecraftAccessKey extends ActiveRecord {
         return $this->hasOne(Account::class, ['id' => 'account_id']);
     }
 
-    public function isActual() : bool {
-        return $this->updated_at + self::LIFETIME >= time();
+    public function isExpired() : bool {
+        return time() > $this->updated_at + self::LIFETIME;
     }
 
 }
diff --git a/common/models/OauthAccessToken.php b/common/models/OauthAccessToken.php
index 9c60bed..8a2dff5 100644
--- a/common/models/OauthAccessToken.php
+++ b/common/models/OauthAccessToken.php
@@ -39,7 +39,7 @@ class OauthAccessToken extends ActiveRecord {
         return true;
     }
 
-    public function isExpired() {
+    public function isExpired() : bool {
         return time() > $this->expire_time;
     }
 
diff --git a/common/validators/UuidValidator.php b/common/validators/UuidValidator.php
new file mode 100644
index 0000000..e0ccced
--- /dev/null
+++ b/common/validators/UuidValidator.php
@@ -0,0 +1,23 @@
+<?php
+namespace common\validators;
+
+use InvalidArgumentException;
+use Ramsey\Uuid\Uuid;
+use yii\validators\Validator;
+
+class UuidValidator extends Validator {
+
+    public $skipOnEmpty = false;
+
+    public $message = '{attribute} must be valid uuid';
+
+    public function validateAttribute($model, $attribute) {
+        try {
+            $uuid = Uuid::fromString($model->$attribute)->toString();
+            $model->$attribute = $uuid;
+        } catch (InvalidArgumentException $e) {
+            $this->addError($model, $attribute, $this->message, []);
+        }
+    }
+
+}
diff --git a/tests/codeception/api/_pages/SessionServerRoute.php b/tests/codeception/api/_pages/SessionServerRoute.php
new file mode 100644
index 0000000..d059c8d
--- /dev/null
+++ b/tests/codeception/api/_pages/SessionServerRoute.php
@@ -0,0 +1,16 @@
+<?php
+namespace tests\codeception\api\_pages;
+
+use yii\codeception\BasePage;
+
+/**
+ * @property \tests\codeception\api\FunctionalTester $actor
+ */
+class SessionServerRoute extends BasePage {
+
+    public function join($params) {
+        $this->route = ['sessionserver/session/join'];
+        $this->actor->sendPOST($this->getUrl(), $params);
+    }
+
+}
diff --git a/tests/codeception/api/functional/sessionserver/JoinCest.php b/tests/codeception/api/functional/sessionserver/JoinCest.php
new file mode 100644
index 0000000..ce7709a
--- /dev/null
+++ b/tests/codeception/api/functional/sessionserver/JoinCest.php
@@ -0,0 +1,111 @@
+<?php
+namespace tests\codeception\api\functional\sessionserver;
+
+use common\models\OauthScope as S;
+use Faker\Provider\Uuid;
+use tests\codeception\api\_pages\SessionServerRoute;
+use tests\codeception\api\functional\_steps\AuthserverSteps;
+use tests\codeception\api\functional\_steps\OauthSteps;
+use tests\codeception\api\FunctionalTester;
+
+class JoinCest {
+
+    /**
+     * @var SessionServerRoute
+     */
+    private $route;
+
+    public function _before(AuthserverSteps $I) {
+        $this->route = new SessionServerRoute($I);
+    }
+
+    public function joinByLegacyAuthserver(AuthserverSteps $I) {
+        $I->wantTo('join to server, using legacy authserver access token');
+        list($accessToken) = $I->amAuthenticated();
+        $this->route->join([
+            'accessToken' => $accessToken,
+            'selectedProfile' => 'df936908-b2e1-544d-96f8-2977ec213022',
+            'serverId' => Uuid::uuid(),
+        ]);
+        $this->expectSuccessResponse($I);
+    }
+
+    public function joinByModernOauth2Token(OauthSteps $I) {
+        $I->wantTo('join to server, using moder oAuth2 generated token');
+        $accessToken = $I->getAccessToken([S::MINECRAFT_SERVER_SESSION]);
+        $this->route->join([
+            'accessToken' => $accessToken,
+            'selectedProfile' => 'df936908-b2e1-544d-96f8-2977ec213022',
+            'serverId' => Uuid::uuid(),
+        ]);
+        $this->expectSuccessResponse($I);
+    }
+
+    public function joinByModernOauth2TokenWithoutPermission(OauthSteps $I) {
+        $I->wantTo('join to server, using moder oAuth2 generated token, but without minecraft auth permission');
+        $accessToken = $I->getAccessToken([S::ACCOUNT_INFO, S::ACCOUNT_EMAIL]);
+        $this->route->join([
+            'accessToken' => $accessToken,
+            'selectedProfile' => 'df936908-b2e1-544d-96f8-2977ec213022',
+            'serverId' => Uuid::uuid(),
+        ]);
+        $I->seeResponseCodeIs(401);
+        $I->seeResponseIsJson();
+        $I->canSeeResponseContainsJson([
+            'error' => 'ForbiddenOperationException',
+            'errorMessage' => 'The token does not have required scope.',
+        ]);
+    }
+
+    public function joinWithExpiredToken(FunctionalTester $I) {
+        $I->wantTo('join to some server with expired accessToken');
+        $this->route->join([
+            'accessToken' => '6042634a-a1e2-4aed-866c-c661fe4e63e2',
+            'selectedProfile' => 'df936908-b2e1-544d-96f8-2977ec213022',
+            'serverId' => Uuid::uuid(),
+        ]);
+        $I->seeResponseCodeIs(401);
+        $I->seeResponseIsJson();
+        $I->canSeeResponseContainsJson([
+            'error' => 'ForbiddenOperationException',
+            'errorMessage' => 'Expired access_token.',
+        ]);
+    }
+
+    public function wrongArguments(FunctionalTester $I) {
+        $I->wantTo('get error on wrong amount of arguments');
+        $this->route->join([
+            'wrong' => 'argument',
+        ]);
+        $I->canSeeResponseCodeIs(400);
+        $I->canSeeResponseIsJson();
+        $I->canSeeResponseContainsJson([
+            'error' => 'IllegalArgumentException',
+            'errorMessage' => 'credentials can not be null.',
+        ]);
+    }
+
+    public function joinWithWrongAccessToken(FunctionalTester $I) {
+        $I->wantTo('join to some server with wrong accessToken');
+        $this->route->join([
+            'accessToken' => Uuid::uuid(),
+            'selectedProfile' => 'df936908-b2e1-544d-96f8-2977ec213022',
+            'serverId' => Uuid::uuid(),
+        ]);
+        $I->seeResponseCodeIs(401);
+        $I->seeResponseIsJson();
+        $I->canSeeResponseContainsJson([
+            'error' => 'ForbiddenOperationException',
+            'errorMessage' => 'Invalid access_token.',
+        ]);
+    }
+
+    private function expectSuccessResponse(FunctionalTester $I) {
+        $I->seeResponseCodeIs(200);
+        $I->seeResponseIsJson();
+        $I->canSeeResponseContainsJson([
+            'id' => 'OK',
+        ]);
+    }
+
+}
diff --git a/tests/codeception/common/unit/validators/UuidValidatorTest.php b/tests/codeception/common/unit/validators/UuidValidatorTest.php
new file mode 100644
index 0000000..ef90735
--- /dev/null
+++ b/tests/codeception/common/unit/validators/UuidValidatorTest.php
@@ -0,0 +1,53 @@
+<?php
+namespace tests\codeception\common\unit\validators;
+
+use Codeception\Specify;
+use common\validators\UuidValidator;
+use Faker\Provider\Uuid;
+use tests\codeception\common\unit\TestCase;
+use yii\base\Model;
+
+class UuidValidatorTest extends TestCase {
+    use Specify;
+
+    public function testValidateAttribute() {
+        $this->specify('expected error if passed empty value', function() {
+            $model = new UuidTestModel();
+            expect($model->validate())->false();
+            expect($model->getErrors('attribute'))->equals(['Attribute must be valid uuid']);
+        });
+
+        $this->specify('expected error if passed invalid string', function() {
+            $model = new UuidTestModel();
+            $model->attribute = '123456789';
+            expect($model->validate())->false();
+            expect($model->getErrors('attribute'))->equals(['Attribute must be valid uuid']);
+        });
+
+        $this->specify('no errors if passed valid uuid', function() {
+            $model = new UuidTestModel();
+            $model->attribute = Uuid::uuid();
+            expect($model->validate())->true();
+        });
+
+        $this->specify('no errors if passed uuid string without dashes and converted to standart value', function() {
+            $model = new UuidTestModel();
+            $originalUuid = Uuid::uuid();
+            $model->attribute = str_replace('-', '', $originalUuid);
+            expect($model->validate())->true();
+            expect($model->attribute)->equals($originalUuid);
+        });
+    }
+
+}
+
+class UuidTestModel extends Model {
+    public $attribute;
+
+    public function rules() {
+        return [
+            ['attribute', UuidValidator::class],
+        ];
+    }
+
+}