diff --git a/src/Plugin/Block/LoginBlock.php b/src/Plugin/Block/LoginBlock.php
new file mode 100644
index 00000000..934d1681
--- /dev/null
+++ b/src/Plugin/Block/LoginBlock.php
@@ -0,0 +1,77 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\oe_authentication\Plugin\Block;
+
+use Drupal\Core\Block\BlockBase;
+use Drupal\Core\Cache\Cache;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\Session\AccountProxyInterface;
+use Drupal\Core\Url;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Provides a block that renders links to login or logout.
+ *
+ * @Block(
+ *  id = "oe_authentication_login_block",
+ *  admin_label = @Translation("EU Login Link Block"),
+ * )
+ */
+class LoginBlock extends BlockBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * Drupal\Core\Session\AccountProxy definition.
+   *
+   * @var \Drupal\Core\Session\AccountProxyInterface
+   */
+  protected $currentUser;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, AccountProxyInterface $current_user) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->currentUser = $current_user;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('current_user')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function build() {
+    if ($this->currentUser->isAnonymous()) {
+      return [
+        '#type' => 'link',
+        '#title' => $this->t('Log in'),
+        '#url' => Url::fromRoute('user.login'),
+      ];
+    }
+
+    return [
+      '#type' => 'link',
+      '#title' => $this->t('Log out'),
+      '#url' => Url::fromRoute('user.logout'),
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCacheContexts() {
+    return Cache::mergeContexts(parent::getCacheContexts(), ['user.roles:anonymous']);
+  }
+
+}
diff --git a/tests/Kernel/LoginBlockTest.php b/tests/Kernel/LoginBlockTest.php
new file mode 100644
index 00000000..28b0b77e
--- /dev/null
+++ b/tests/Kernel/LoginBlockTest.php
@@ -0,0 +1,83 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\Tests\oe_authentication\Kernel;
+
+use Drupal\Core\Url;
+use Drupal\KernelTests\KernelTestBase;
+use Drupal\user\Entity\User;
+use Symfony\Component\DomCrawler\Crawler;
+
+/**
+ * Test login block rendering.
+ */
+class LoginBlockTest extends KernelTestBase {
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = [
+    'block',
+    'oe_authentication',
+    'system',
+    'user',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->installConfig(['system', 'block', 'user']);
+    $this->installEntitySchema('user');
+    $this->installSchema('system', ['sequences']);
+  }
+
+  /**
+   * Test login block rendering.
+   */
+  public function testLoginBlockRendering(): void {
+
+    // Setup and render login block.
+    $block_manager = $this->container->get('plugin.manager.block');
+    $renderer = $this->container->get('renderer');
+
+    /** @var \Drupal\oe_authentication\Plugin\Block\LoginBlock $plugin_block */
+    $plugin_block = $block_manager->createInstance('oe_authentication_login_block');
+    $build = $plugin_block->build();
+    $block = (string) $renderer->renderRoot($build);
+
+    $crawler = new Crawler($block);
+
+    // Make sure the login link is present.
+    $link = $crawler->filter('a');
+    $this->assertEquals(t('Log in'), $link->text());
+    $this->assertEquals(Url::fromRoute('user.login')->toString(), $link->attr('href'));
+
+    // Create a user to login.
+    $user1 = User::create([
+      'name' => 'oe_user1',
+      'mail' => 'oe_user1@example.com',
+    ]);
+
+    $user1->activate();
+    $user1->save();
+
+    // Simulate a login of this user.
+    $this->container->get('current_user')->setAccount($user1);
+
+    // Render the block again.
+    $build = $plugin_block->build();
+    $block = (string) $renderer->renderRoot($build);
+
+    // Asserts if the text changed, and log out text is now present.
+    $crawler = new Crawler($block);
+    $link = $crawler->filter('a');
+    $this->assertEquals(t('Log out'), $link->text());
+    $this->assertEquals(Url::fromRoute('user.logout')->toString(), $link->attr('href'));
+  }
+
+}