diff --git a/src/ClaimsAwareInterface.php b/src/ClaimsAwareInterface.php
new file mode 100644
index 0000000..47d0503
--- /dev/null
+++ b/src/ClaimsAwareInterface.php
@@ -0,0 +1,11 @@
+<?php
+
+namespace Antenna;
+
+interface ClaimsAwareInterface
+{
+    /**
+     * @return [string]mixed a key/value array of additional claims
+     */
+    public function getClaims();
+}
diff --git a/src/Coder.php b/src/Coder.php
index b8f4602..4ca2400 100644
--- a/src/Coder.php
+++ b/src/Coder.php
@@ -17,7 +17,7 @@ public function __construct($secret)
 
     public function encode(WebToken $webToken)
     {
-        $payload = [
+        $payload = $webToken->all() + [
             'sub' => $webToken->getSubject(),
             'iat' => $webToken->getIssuedAt()->getTimestamp(),
             'exp' => $webToken->getExpireAt()->getTimestamp(),
@@ -33,15 +33,19 @@ public function encode(WebToken $webToken)
      */
     public function decode($encoded)
     {
-        $payload = (array) JWT::decode($encoded, $this->secret, [$this->algoritm]) + [
+        $defaults = [
             'sub' => null,
             'iat' => null,
             'exp' => null,
         ];
 
+        $payload = (array) JWT::decode($encoded, $this->secret, [$this->algoritm]) + $defaults;
+
+        $claims = array_diff_key($payload, $defaults);
+
         $expireAt = new DateTimeImmutable('@'.$payload['exp']);
         $issuedAt = new DateTimeImmutable('@'.$payload['iat']);
 
-        return new WebToken($payload['sub'], $issuedAt, $expireAt);
+        return new WebToken($payload['sub'], $issuedAt, $expireAt, $claims);
     }
 }
diff --git a/src/Security/UsernamePasswordAuthenticator.php b/src/Security/UsernamePasswordAuthenticator.php
index 7d83ead..b52569c 100644
--- a/src/Security/UsernamePasswordAuthenticator.php
+++ b/src/Security/UsernamePasswordAuthenticator.php
@@ -4,6 +4,7 @@
 
 use Antenna\Coder;
 use Antenna\WebToken;
+use Antenna\ClaimsAwareInterface;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpFoundation\JsonResponse;
@@ -37,9 +38,9 @@ class UsernamePasswordAuthenticator implements
     private $coder;
 
     /**
-     * @param UserCheckerInterface    $userChecker
+     * @param UserCheckerInterface         $userChecker
      * @param UserPasswordEncoderInterface $encoder
-     * @param Coder                   $coder
+     * @param Coder                        $coder
      */
     public function __construct(
         UserCheckerInterface $userChecker,
@@ -105,10 +106,19 @@ public function onAuthenticationFailure(Request $request, AuthenticationExceptio
 
     public function onAuthenticationSuccess(Request $request, TokenInterface $token)
     {
-        $webToken = new WebToken($token->getUsername(), date_create_immutable(), date_create_immutable('+7 days'));
+        $claims = [];
+        $user = $token->getUser();
+
+        if ($user instanceof ClaimsAwareInterface) {
+            $claims = $user->getClaims();
+        }
+
+        $webToken = new WebToken(
+            $token->getUsername(), date_create_immutable(), date_create_immutable('+7 days'), $claims
+        );
 
         return new JsonResponse([
-            'token' => $this->coder->encode($webToken)
+            'token' => $this->coder->encode($webToken),
         ]);
     }
 }
diff --git a/src/WebToken.php b/src/WebToken.php
index 9d864ff..4a5c822 100644
--- a/src/WebToken.php
+++ b/src/WebToken.php
@@ -4,17 +4,33 @@
 
 use DateTimeInterface;
 
+/**
+ * Represents part of a Json Web Token.
+ *
+ * Its main relation is "claims" and as such, the methods for interacting
+ * with these follow the Symfony Convention http://symfony.com/doc/current/contributing/code/conventions.html#method-names
+ *
+ * Not this is an immutable class.
+ */
 class WebToken
 {
     private $subject;
     private $issuedAt;
     private $expireAt;
+    private $claims = [];
 
-    public function __construct($subject, DateTimeInterface $issuedAt, DateTimeInterface $expireAt)
+    /**
+     * @param string            $subject  The sub (subject) claim identifies the principal that is the subject of the JWT.
+     * @param DateTimeInterface $issuedAt The iat (issued at) claim identifies the time at which the JWT was issued.
+     * @param DateTimeInterface $expireAt The exp (expiration time) claim identifies the expiration time.
+     * @param [string]mixed Additional claims that is not required.
+     */
+    public function __construct($subject, DateTimeInterface $issuedAt, DateTimeInterface $expireAt, $claims = [])
     {
         $this->subject = $subject;
         $this->issuedAt = $issuedAt;
         $this->expireAt = $expireAt;
+        $this->claims = $claims;
     }
 
     public function getSubject()
@@ -31,4 +47,24 @@ public function getExpireAt()
     {
         return $this->expireAt;
     }
+
+    public function all()
+    {
+        return $this->claims;
+    }
+
+    public function keys()
+    {
+        return array_keys($this->claims);
+    }
+
+    public function has($claim)
+    {
+        return array_key_exists($claim, $this->claims);
+    }
+
+    public function get($claim, $default = null)
+    {
+        return $this->has($claim) ? $this->claims[$claim] : $default;
+    }
 }
diff --git a/tests/CoderTest.php b/tests/CoderTest.php
index 9b818f9..843e2de 100644
--- a/tests/CoderTest.php
+++ b/tests/CoderTest.php
@@ -7,20 +7,41 @@
 
 class CoderTest extends \PHPUnit_Framework_TestCase
 {
-    public function testCoding()
+    public function setUp()
     {
-        $coder = new Coder('shared_secret');
+        $this->coder = new Coder('shared_secret');
+    }
 
+    public function testCoding()
+    {
         $utc = new \DateTimeZone('UTC');
         $issuedAt = date_create_immutable('now');
         $expireAt = date_create_immutable('+1 year');
 
-        $webToken = $coder->decode($coder->encode(
-            new WebToken('my_subject', $issuedAt, $expireAt)
-        ));
+        $webToken = $this->coder->decode(
+            $this->coder->encode(
+                new WebToken('my_subject', $issuedAt, $expireAt)
+            )
+        );
 
         $this->assertEquals('my_subject', $webToken->getSubject());
         $this->assertEquals($issuedAt->getTimestamp(), $webToken->getIssuedAt()->getTimestamp());
         $this->assertEquals($expireAt->getTimestamp(), $webToken->getExpireAt()->getTimestamp());
     }
+
+    public function testClaims()
+    {
+        $claims = [
+            'administrator' => 1,
+            'roles' => ['ROLE_USER', 'ROLE_SUPER_ADMIN'],
+        ];
+
+        $webToken = $this->coder->decode(
+            $this->coder->encode(
+                new WebToken('my_subject', date_create(), date_create('+1 year'), $claims)
+            )
+        );
+
+        $this->assertEquals($claims, $webToken->all());
+    }
 }