diff --git a/migrations/Version20230730131708.php b/migrations/Version20230730131708.php
new file mode 100644
index 00000000..2d5c0024
--- /dev/null
+++ b/migrations/Version20230730131708.php
@@ -0,0 +1,31 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+/**
+ * Auto-generated Migration: Please modify to your needs!
+ */
+final class Version20230730131708 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return '';
+    }
+
+    public function up(Schema $schema): void
+    {
+        // this up() migration is auto-generated, please modify it to your needs
+        $this->addSql('ALTER TABLE oauth_tokens CHANGE token token LONGTEXT DEFAULT NULL, CHANGE refresh_token refresh_token LONGTEXT DEFAULT NULL');
+    }
+
+    public function down(Schema $schema): void
+    {
+        // this down() migration is auto-generated, please modify it to your needs
+        $this->addSql('ALTER TABLE oauth_tokens CHANGE token token VARCHAR(255) DEFAULT NULL, CHANGE refresh_token refresh_token VARCHAR(255) NOT NULL');
+    }
+}
diff --git a/src/Entity/OAuthToken.php b/src/Entity/OAuthToken.php
index 30a8feef..b1534a4d 100644
--- a/src/Entity/OAuthToken.php
+++ b/src/Entity/OAuthToken.php
@@ -39,26 +39,34 @@ use League\OAuth2\Client\Token\AccessTokenInterface;
 class OAuthToken extends AbstractNamedDBElement implements AccessTokenInterface
 {
     /** @var string|null The short-term usable OAuth2 token */
-    #[ORM\Column(type: 'string', nullable: true)]
+    #[ORM\Column(type: 'text', nullable: true)]
     private ?string $token = null;
 
     /** @var \DateTimeInterface The date when the token expires */
     #[ORM\Column(type: Types::DATETIME_IMMUTABLE, nullable: true)]
     private ?\DateTimeInterface $expires_at = null;
 
-    /** @var string The refresh token for the OAuth2 auth */
-    #[ORM\Column(type: 'string')]
-    private string $refresh_token = '';
+    /** @var string|null The refresh token for the OAuth2 auth */
+    #[ORM\Column(type: 'text', nullable: true)]
+    private ?string $refresh_token = null;
 
+    /**
+     * The default expiration time for a authorization token, if no expiration time is given
+     */
     private const DEFAULT_EXPIRATION_TIME = 3600;
 
-    public function __construct(string $name, string $refresh_token, string $token = null, \DateTimeInterface $expires_at = null)
+    public function __construct(string $name, ?string $refresh_token, ?string $token = null, \DateTimeInterface $expires_at = null)
     {
         //If token is given, you also have to give the expires_at date
         if ($token !== null && $expires_at === null) {
             throw new \InvalidArgumentException('If you give a token, you also have to give the expires_at date');
         }
 
+        //If no refresh_token is given, the token is a client credentials grant token, which must have a token
+        if ($refresh_token === null && $token === null) {
+            throw new \InvalidArgumentException('If you give no refresh_token, you have to give a token!');
+        }
+
         $this->name = $name;
         $this->refresh_token = $refresh_token;
         $this->expires_at = $expires_at;
@@ -109,6 +117,16 @@ class OAuthToken extends AbstractNamedDBElement implements AccessTokenInterface
         return $this->expires_at->getTimestamp() < time();
     }
 
+    /**
+     * Returns true if this token is a client credentials grant token (meaning it has no refresh token), and
+     * needs to be refreshed via the client credentials grant.
+     * @return bool
+     */
+    public function isClientCredentialsGrant(): bool
+    {
+        return $this->refresh_token === null;
+    }
+
     public function replaceWithNewToken(AccessTokenInterface $accessToken): void
     {
         $this->token = $accessToken->getToken();
diff --git a/src/Services/OAuth/OAuthTokenManager.php b/src/Services/OAuth/OAuthTokenManager.php
index 020eead7..1f6f6b51 100644
--- a/src/Services/OAuth/OAuthTokenManager.php
+++ b/src/Services/OAuth/OAuthTokenManager.php
@@ -39,9 +39,9 @@ final class OAuthTokenManager
      * Saves the given token to the database, so it can be retrieved later
      * @param  string  $app_name
      * @param  AccessTokenInterface  $token
-     * @return void
+     * @return OAuthToken The saved token as database entity
      */
-    public function saveToken(string $app_name, AccessTokenInterface $token): void
+    public function saveToken(string $app_name, AccessTokenInterface $token): OAuthToken
     {
         //Check if we already have a token for this app
         $tokenEntity = $this->entityManager->getRepository(OAuthToken::class)->findOneBy(['name' => $app_name]);
@@ -54,7 +54,7 @@ final class OAuthTokenManager
             $this->entityManager->flush($tokenEntity);
 
             //We are done
-            return;
+            return $tokenEntity;
         }
 
         //If the token was not existing, we create a new one
@@ -63,7 +63,7 @@ final class OAuthTokenManager
         //@phpstan-ignore-next-line
         $this->entityManager->flush($tokenEntity);
 
-        return;
+        return $tokenEntity;
     }
 
     /**
@@ -102,7 +102,14 @@ final class OAuthTokenManager
         }
 
         $client = $this->clientRegistry->getClient($app_name);
-        $new_token = $client->refreshAccessToken($token->getRefreshToken());
+
+        //Check if the token is refreshable or if it is an client credentials token
+        if ($token->isClientCredentialsGrant()) {
+            $new_token = $client->getOAuth2Provider()->getAccessToken('client_credentials');
+        } else {
+            //Otherwise we can use the refresh token to get a new access token
+            $new_token = $client->refreshAccessToken($token->getRefreshToken());
+        }
 
         //Persist the token
         $token->replaceWithNewToken($new_token);
@@ -139,4 +146,20 @@ final class OAuthTokenManager
         //And return the new token
         return $token->getToken();
     }
+
+    /**
+     * Retrieves an access token for the given app name using the client credentials grant (so no user flow is needed)
+     * The app_name must be registered in the knpu_oauth2_client.yaml
+     * The token is saved to the database, and afterward can be used as usual
+     * @param  string  $app_name
+     * @return OAuthToken
+     */
+    public function retrieveClientCredentialsToken(string $app_name): OAuthToken
+    {
+        $client = $this->clientRegistry->getClient($app_name);
+        $access_token = $client->getOAuth2Provider()->getAccessToken('client_credentials');
+
+
+        return $this->saveToken($app_name, $access_token);
+    }
 }
\ No newline at end of file