diff --git a/views/index.html b/views/index.html
index 46c5f52..3fffa92 100644
--- a/views/index.html
+++ b/views/index.html
@@ -37,6 +37,11 @@
           <li><a href="/api">ajax API</a></li>
         </ul>
       </section>
+      <p>
+        API small documentation:<br>
+        <code>{"fuzIsOpen":true,"lastSeen":"2019-11-03T16:25:24.385Z"}</code><br>
+        Means that the last notification sent by the presence button was at 2019-11-03T16:25:24.385Z and it was saying that the Fuz was open at the time. If it's been a while since last notification (lastSeen), we can conclude the Fuz is now closed.
+      </p>
     </main>
 
     <footer>